What is chromosome 17?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 17, one copy inherited from each parent, form one of the pairs. Chromosome 17 spans about 81 million DNA building blocks (base pairs) and represents between 2.5 and 3 percent of the total DNA in cells.
Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 17 likely contains 1,200 to 1,300 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 17 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 17 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 17. This list of disorders associated with genes on chromosome 17 provides links to additional information.
Changes in the structure or number of copies of a chromosome can also cause problems with health and development. The following chromosomal conditions are associated with such changes in chromosome 17.

acute promyelocytic leukemia

A type of blood cancer known as acute promyelocytic leukemia is caused by a rearrangement (translocation) of genetic material between chromosomes 15 and 17. This translocation, written as t(15;17), fuses part of the PML gene from chromosome 15 with part of the RARA gene from chromosome 17. This mutation is acquired during a person's lifetime and is present only in certain cells. This type of genetic change, called a somatic mutation, is not inherited. The t(15;17) translocation is called a balanced reciprocal translocation because the pieces of chromosome are exchanged with each other (reciprocal) and no genetic material is gained or lost (balanced). The protein produced from this fused gene is known as PML-RARα.
The PML-RARα protein functions differently than the protein products from the normal PML and RARA genes. The RARA gene on chromosome 17 provides instructions for making a transcription factor called the retinoic acid receptor alpha (RARα). A transcription factor is a protein that attaches (binds) to specific regions of DNA and helps control the activity (transcription) of particular genes. Normally, the RARα protein controls the activity of genes important for the maturation (differentiation) of immature white blood cells beyond a particular stage called the promyelocyte. The PML gene on chromosome 15 provides instructions for a protein that acts as a tumor suppressor, which means it prevents cells from growing and dividing too rapidly or in an uncontrolled way. The PML protein blocks cell growth and division (proliferation) and induces self-destruction (apoptosis) in combination with other proteins. The PML-RARα protein interferes with the normal function of both the PML and the RARα proteins. As a result, blood cells are stuck at the promyelocyte stage, and they proliferate abnormally. Excess promyelocytes accumulate in the bone marrow and normal white blood cells cannot form, leading to acute promyelocytic leukemia.

dermatofibrosarcoma protuberans

Translocation of genetic material between chromosomes 17 and 22, written as t(17;22), causes a rare type of skin cancer known as dermatofibrosarcoma protuberans. This translocation fuses part of the COL1A1 gene from chromosome 17 with part of the PDGFB gene from chromosome 22. The translocation is found on one or more extra chromosomes that can be either linear or circular. When circular, the extra chromosomes are known as supernumerary ring chromosomes. This mutation is acquired during a person's lifetime and is present only in certain cells. This type of genetic change, called a somatic mutation, is not inherited.
The fused COL1A1-PDGFB gene provides instructions for making a combined (fusion) protein that researchers believe ultimately functions like the active PDGFB protein. In the translocation, the PDGFB gene loses the part of its DNA that limits its activity, and production of the COL1A1-PDGFB fusion protein is controlled by COL1A1 gene sequences. As a result, the gene fusion leads to the production of a larger amount of active PDGFB protein than normal. Active PDGFB protein signals for cell growth and division (proliferation) and maturation (differentiation). Excess PDGFB protein abnormally stimulates cells to proliferate and differentiate, leading to the tumor formation seen in dermatofibrosarcoma protuberans.

Koolen-de Vries syndrome

Deletion of a small amount of genetic material (a microdeletion) on chromosome 17 can cause Koolen-de Vries syndrome. This disorder is characterized by developmental delay, intellectual disability, a cheerful and sociable disposition, and a variety of physical abnormalities.
Most people with Koolen-de Vries syndrome are missing a sequence of about 500,000 base pairs, also written as 500 kilobases (kb), at position q21.31 on chromosome 17. The exact size of the deletion varies among affected individuals, but it contains at least six genes including KANSL1. This deletion affects one of the two copies of chromosome 17 in each cell.
Because mutations in the KANSL1 gene cause the same signs and symptoms as the deletion, researchers have concluded that the loss of this gene accounts for the features of Koolen-de Vries syndrome. The protein produced from the KANSL1 gene is involved in controlling the activity of other genes and plays an important role in the development and function of many parts of the body. Although the loss of this gene impairs normal development and function, its relationship to the specific features of Koolen-de Vries syndrome is unclear.
While Koolen-de Vries syndrome is usually not inherited, most individuals with the condition caused by a deletion have had at least one parent with a common variant of the 17q21.31 region of chromosome 17 called the H2 lineage. This variant is found in 20 percent of people of European and Middle Eastern descent, although it is rare in other populations. In the H2 lineage, a 900 kb segment of DNA, which includes the region deleted in most cases of Koolen-de Vries syndrome, has undergone an inversion. An inversion involves two breaks in a chromosome; the resulting piece of DNA is reversed and reinserted into the chromosome.
People with the H2 lineage have no health problems related to the inversion. However, genetic material can be lost or duplicated when the inversion is passed to the next generation. Researchers believe that a parental inversion is probably necessary for a child to have the 17q21.31 microdeletion most often associated with Koolen-de Vries syndrome, but other, unknown factors are also thought to play a role. So while the inversion is very common, only an extremely small percentage of parents with the inversion have a child affected by Koolen-de Vries syndrome.

Miller-Dieker syndrome

Miller-Dieker syndrome is caused by a deletion of genetic material near the end of the short (p) arm of chromosome 17. The signs and symptoms of Miller-Dieker syndrome are related to the loss of multiple genes in this region. The size of the deletion varies among affected individuals. The loss of a particular gene on chromosome 17, called PAFAH1B1, is responsible for the syndrome's characteristic sign of lissencephaly, a problem with brain development in which the surface of the brain is abnormally smooth. The loss of another gene, called YWHAE, in the same region of chromosome 17 increases the severity of lissencephaly in people with Miller-Dieker syndrome. Additional genes in the deleted region contribute to the varied features of Miller-Dieker syndrome.

Smith-Magenis syndrome

Most people with Smith-Magenis syndrome have a deletion of genetic material from a specific part of chromosome 17 called the Smith-Magenis syndrome critical region. This region is located on the short (p) arm of chromosome 17 at position 11.2 (written as 17p11.2). Although this region contains multiple genes, researchers believe that the loss of one particular gene, RAI1, in each cell is responsible for most of the physical, mental, and behavioral features of Smith-Magenis syndrome. The loss of other genes in the deleted region may help explain why the signs and symptoms of this condition vary among affected individuals.

other cancers

Changes in chromosome 17 have been identified in several additional types of human cancer. These genetic changes are somatic, which means they are acquired during a person's lifetime and are present only in certain cells. A particular chromosomal abnormality called an isochromosome 17q occurs frequently in some cancers. This abnormal version of chromosome 17 has two long (q) arms instead of one long arm and one short (p) arm. As a result, the chromosome has an extra copy of some genes and is missing copies of other genes.
An isochromosome 17q is commonly found in a cancer of blood-forming tissue called chronic myeloid leukemia (CML). It also has been identified in certain solid tumors, including a type of brain tumor called a medulloblastoma and tumors of the brain and spinal cord known as primitive neuroectodermal tumors. Although an isochromosome 17q probably plays a role in both the development and progression of these cancers, the specific genetic changes related to cancer growth are unknown.

other chromosomal conditions

Other changes in the number or structure of chromosome 17 can have a variety of effects, including intellectual disability, delayed development, characteristic facial features, weak muscle tone (hypotonia), and short stature. These changes include an extra piece of chromosome 17 in each cell (partial trisomy 17), a missing segment of the chromosome in each cell (partial monosomy 17), and a circular structure called a ring chromosome 17. Ring chromosomes occur when a chromosome breaks in two places and the ends of the chromosome arms fuse together to form a circular structure.

Is there a standard way to diagram chromosome 17?

Geneticists use diagrams called ideograms as a standard representation for chromosomes. Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope. These bands are used to describe the location of genes on each chromosome.

What is chromosome 16?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 16, one copy inherited from each parent, form one of the pairs. Chromosome 16 spans more than 90 million DNA building blocks (base pairs) and represents almost 3 percent of the total DNA in cells.
Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 16 likely contains 800 to 900 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 16 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 16 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 16. This list of disorders associated with genes on chromosome 16 provides links to additional information.
Changes in the structure or number of copies of a chromosome can also cause problems with health and development. The following chromosomal conditions are associated with such changes in chromosome 16.

alveolar capillary dysplasia with misalignment of pulmonary veins

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) is a disorder that affects the development of blood vessels in the lungs. It can be caused by a deletion of genetic material on chromosome 16 in a region known as 16q24.1. This region includes several genes, including the FOXF1 gene. The protein produced from the FOXF1 gene is a transcription factor, which means that it attaches (binds) to specific regions of DNA and helps control the activity of many other genes. The FOXF1 protein helps regulate the development of the lungs and the gastrointestinal tract. Genetic changes that result in a nonfunctional FOX1 protein interfere with the development of pulmonary blood vessels and cause ACD/MPV. Affected infants may also have gastrointestinal abnormalities.
Researchers suggest that deletions resulting in the loss of other genes in this region of chromosome 16 probably cause the additional abnormalities seen in some infants with this disorder. Like FOXF1, these genes also provide instructions for making transcription factors that regulate development of various body systems before birth.

cancers

Changes in the structure of chromosome 16 are associated with several types of cancer. These genetic changes are somatic, which means they are acquired during a person's lifetime and are present only in certain cells. In some cases, chromosomal rearrangements called translocations disrupt the region of chromosome 16 that contains the CREBBP gene. The protein produced from this gene normally plays a role in regulating cell growth and division, which helps prevent the development of cancers.
Researchers have found a translocation between chromosome 8 and chromosome 16 that disrupts the CREBBP gene in some people with a cancer of blood-forming cells called acute myeloid leukemia (AML). Another translocation involving the CREBBP gene, which rearranges pieces of chromosomes 11 and 16, has been found in some people who have undergone cancer treatment. This chromosomal change is associated with the later development of AML and two other cancers of blood-forming tissues (chronic myelogenous leukemia and myelodysplastic syndrome). These are sometimes described as treatment-related cancers because the translocation between chromosomes 11 and 16 occurs following chemotherapy for other forms of cancer.
A chromosomal rearrangement called an inversion has been identified in rare cases of AML. This inversion involves the breakage of chromosome 16 in two places; the resulting piece of DNA is reversed and re-inserted into the chromosome. This form of AML is characterized by a high rate of remission and a favorable outcome. Unlike the somatic changes described earlier, this chromosomal rearrangement may be inherited from a parent.

16p11.2 deletion syndrome

16p11.2 deletion syndrome is caused by a deletion of about 600,000 DNA building blocks (base pairs), also written as 600 kilobases (kb), at position 11.2 on the short (p) arm of chromosome 16. This deletion affects one of the two copies of chromosome 16 in each cell. The 600 kb region contains at least 25 genes, and in many cases little is known about their function. Researchers are working to determine the missing genes that contribute to the features of 16p11.2 deletion syndrome, which include delayed development, intellectual disability, and developmental disorders that affect communication and social interaction (autism spectrum disorders).
Having a 16p11.2 deletion does not always lead to autism spectrum disorders or intellectual disability. Most people with the deletion have some of these symptoms, but others do not. Although some people have this deletion without serious consequences, they can still pass it to their children, who may be more severely affected.

Rubinstein-Taybi syndrome

Some cases of severe Rubinstein-Taybi syndrome (also known as chromosome 16p13.3 deletion syndrome) have resulted from a deletion of genetic material from the short (p) arm of chromosome 16. When this deletion is present in all of the body's cells, it can cause serious complications such as a failure to gain weight and grow at the expected rate (failure to thrive) and an increased risk of life-threatening infections. Affected individuals also have many of the typical features of Rubinstein-Taybi syndrome, including intellectual disability, distinctive facial features, and broad thumbs and first toes. Infants born with the severe form of this disorder usually survive only into early childhood.
Several genes are missing as a result of the deletion in the short arm of chromosome 16. The deleted region includes the CREBBP gene, which is often mutated or missing in people with the typical features of Rubinstein-Taybi syndrome. Researchers believe that the loss of additional genes in this region probably accounts for the serious complications associated with severe Rubinstein-Taybi syndrome.

other chromosomal conditions

Trisomy 16 occurs when cells have three copies of chromosome 16 instead of the usual two copies. Full trisomy 16, which occurs when all of the body's cells contain an extra copy of chromosome 16, is not compatible with life. A similar but less severe condition called mosaic trisomy 16 occurs when only some of the body's cells have an extra copy of chromosome 16. The signs and symptoms of mosaic trisomy 16 vary widely and can include slow growth before birth (intrauterine growth retardation), delayed development, and heart defects.
Duplication of the same 600 kb segment of chromosome 16 that is missing in 16p11.2 deletion syndrome may result in similar symptoms as the deletion in some individuals. People with this duplication may have developmental problems including autism spectrum disorder, language delay, and learning disability. The duplication appears to have a milder effect than the deletion, with a higher proportion of individuals with this chromosomal change showing no apparent disability. These individuals can still pass along the duplication to their children, who may have symptoms of this condition.
Other changes in the number or structure of chromosome 16 can have a variety of effects. Intellectual disability, delayed growth and development, distinctive facial features, weak muscle tone (hypotonia), heart defects, and other medical problems are common. Frequent changes to chromosome 16 include an extra segment of the short (p) or long (q) arm of the chromosome in each cell (partial trisomy 16p or 16q) and a missing segment of the long arm of the chromosome in each cell (partial monosomy 16q).

Is there a standard way to diagram chromosome 16?

Geneticists use diagrams called ideograms as a standard representation for chromosomes. Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope. These bands are used to describe the location of genes on each chromosome.

What is chromosome 15?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 15, one copy inherited from each parent, form one of the pairs. Chromosome 15 spans more than 102 million DNA building blocks (base pairs) and represents more than 3 percent of the total DNA in cells.
Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 15 likely contains 600 to 700 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 15 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 15 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 15. This list of disorders associated with genes on chromosome 15 provides links to additional information.
Changes in the structure or number of copies of a chromosome can also cause problems with health and development. The following chromosomal conditions are associated with such changes in chromosome 15.

acute promyelocytic leukemia

A type of blood cancer known as acute promyelocytic leukemia is caused by a rearrangement (translocation) of genetic material between chromosomes 15 and 17. This translocation, written as t(15;17), fuses part of the PML gene from chromosome 15 with part of the RARA gene from chromosome 17. This mutation is acquired during a person's lifetime and is present only in certain cells. This type of genetic change, called a somatic mutation, is not inherited. The t(15;17) translocation is called a balanced reciprocal translocation because the pieces of chromosome are exchanged with each other (reciprocal) and no genetic material is gained or lost (balanced). The protein produced from this fused gene is known as PML-RARα.
The PML-RARα protein functions differently than the protein products from the normal PML and RARA genes. The PML gene on chromosome 15 provides instructions for a protein that acts as a tumor suppressor, which means it prevents cells from growing and dividing too rapidly or in an uncontrolled way. The PML protein blocks cell growth and division (proliferation) and induces self-destruction (apoptosis) in combination with other proteins. The RARA gene on chromosome 17 provides instructions for making a transcription factor called the retinoic acid receptor alpha (RARα). A transcription factor is a protein that attaches (binds) to specific regions of DNA and helps control the activity of particular genes. Normally, the RARα protein controls the activity (transcription) of genes important for the maturation (differentiation) of immature white blood cells beyond a particular stage called the promyelocyte. The PML-RARα protein interferes with the normal function of both the PML and the RARα proteins. As a result, blood cells are stuck at the promyelocyte stage, and they proliferate abnormally. Excess promyelocytes accumulate in the bone marrow and normal white blood cells cannot form, leading to acute promyelocytic leukemia.

Angelman syndrome

Angelman syndrome results from a loss of gene activity (expression) in a specific part of chromosome 15 in each cell. This region is located on the long (q) arm of the chromosome and is designated 15q11-q13. This region contains a gene called UBE3A that, when mutated or absent, likely causes the characteristic neurologic features of Angelman syndrome.
People normally inherit one copy of the UBE3A gene from each parent, and both copies of this gene are turned on (active) in many of the body's tissues. In certain areas of the brain, however, only the copy inherited from a person's mother (the maternal copy) is active. This parent-specific gene activation results from a phenomenon called genomic imprinting. If the maternal copy is lost because of a chromosomal change or a gene mutation, a person will have no working copies of the UBE3A gene in some parts of the brain.
In most cases (about 70 percent), Angelman syndrome results from a deletion in the maternal copy of chromosome 15. This chromosomal change deletes the region of chromosome 15 that includes the UBE3A gene. Because the copy of the UBE3A gene inherited from a person's father (the paternal copy) is normally inactive in certain parts of the brain, a deletion in the maternal chromosome 15 leaves no active copies of the UBE3A gene in these brain regions.
In 3 percent to 7 percent of cases of Angelman syndrome, the condition results when a person inherits two copies of chromosome 15 from his or her father instead of one copy from each parent. This phenomenon is called paternal uniparental disomy (UPD). People with paternal UPD for chromosome 15 have two copies of the UBE3A gene, but they are both inherited from the father and are therefore inactive in the brain.
About 10 percent of cases of Angelman syndrome are caused by a mutation in the UBE3A gene, and another 3 percent results from a defect in the DNA region that controls the activation of the UBE3A gene and other genes on the maternal copy of chromosome 15. In a small percentage of cases, Angelman syndrome is caused by a chromosomal rearrangement (translocation) or by a mutation in a gene other than UBE3A. These genetic changes abnormally inactivate the UBE3A gene.

isodicentric chromosome 15 syndrome

Isodicentric chromosome 15 syndrome results from the presence of an abnormal extra chromosome, called an isodicentric chromosome 15, in each cell. An isodicentric chromosome contains mirror-image segments of genetic material and has two constriction points (centromeres), rather than one centromere as in normal chromosomes. In isodicentric chromosome 15 syndrome, the isodicentric chromosome is made up of two extra copies of a segment of genetic material from chromosome 15, attached end-to-end. Typically this copied genetic material includes the 15q11-q13 region.
Cells normally have two copies of each chromosome, one inherited from each parent. In people with isodicentric chromosome 15 syndrome, cells have the usual two copies of chromosome 15 plus the two extra copies of the segment of genetic material in the isodicentric chromosome. The extra genetic material disrupts the normal course of development, causing the characteristic features of this disorder. These features include weak muscle tone (hypotonia), intellectual disability, recurrent seizures (epilepsy), characteristics of autism or related developmental disorders affecting communication and social interaction, and other behavioral problems. Some individuals with isodicentric chromosome 15 whose copied genetic material does not include the 15q11-q13 region do not show signs or symptoms of the condition.

15q13.3 microdeletion

15q13.3 microdeletion is a chromosomal change in which a small piece of chromosome 15 is deleted in each cell. The deletion occurs on the long (q) arm of the chromosome at a position designated q13.3. Most people with a 15q13.3 microdeletion are missing a sequence of about 2 million DNA building blocks (base pairs), also written as 2 megabases (Mb). The exact size of the deleted region varies, but it typically contains at least six genes. It is unclear how a loss of these genes increases the risk of intellectual disability, seizures, behavioral problems, and psychiatric disorders in some individuals with a 15q13.3 microdeletion.
Other people with a 15q13.3 microdeletion have no obvious signs or symptoms related to the chromosomal change. In these individuals, the microdeletion is often detected when they undergo genetic testing because they have an affected relative. It is unknown why 15q13.3 microdeletion causes cognitive and behavioral problems in some individuals but few or no health problems in others. Researchers believe that additional genetic or environmental factors may be involved.

15q24 microdeletion

15q24 microdeletion is a chromosomal change in which a small piece of chromosome 15 is deleted in each cell. Specifically, affected individuals are missing between 1.7 Mb and 6.1 Mb of DNA at position q24 on chromosome 15. The exact size of the deletion varies, but all individuals are missing the same 1.2 Mb region. This region contains several genes that are thought to be important for normal development. It is unclear how a loss of these genes leads to intellectual disability, distinctive facial features, and other abnormalities often seen in people with a 15q24 microdeletion.

Prader-Willi syndrome

Prader-Willi syndrome is caused by a loss of active genes in a region of chromosome 15. This region is located on the long (q) arm of the chromosome and is designated 15q11-q13. It is the same part of chromosome 15 that is usually affected in people with Angelman syndrome, although different genes are associated with the two disorders. People can have either Prader-Willi syndrome or Angelman syndrome, but they typically cannot have both.
People normally inherit one copy of chromosome 15 from each parent. Some genes on this chromosome are turned on (active) only on the copy inherited from a person's father (the paternal copy). This parent-specific gene activation results from a phenomenon called genomic imprinting.
In about 70 percent of cases, Prader-Willi syndrome occurs when the 15q11-q13 region of the paternal chromosome 15 is deleted in each cell. A person with this chromosomal change will be missing certain critical genes in this region because the genes on the paternal copy have been deleted, and the genes on the maternal copy are turned off (inactive). Researchers are working to identify which missing genes are associated with the characteristic features of Prader-Willi syndrome.
In about 25 percent of cases, people with Prader-Willi syndrome inherit two copies of chromosome 15 from their mother instead of one copy from each parent. This phenomenon is called maternal uniparental disomy. A person with two maternal copies of chromosome 15 will have no active copies of certain genes in the 15q11-q13 region.
In a small percentage of cases, Prader-Willi syndrome is caused by a chromosomal rearrangement called a translocation. Rarely, the condition results from a mutation or other defect that abnormally inactivates genes on the paternal copy of chromosome 15.

sensorineural deafness and male infertility

Sensorineural deafness and male infertility is caused by a deletion of genetic material on the long (q) arm of chromosome 15. The symptoms of sensorineural deafness and male infertility are related to the loss of multiple genes in this region. The size of the deletion varies among affected individuals. Researchers have determined that the loss of a particular gene on chromosome 15, STRC, is responsible for hearing loss in affected individuals. The loss of another gene, CATSPER2, in the same region of chromosome 15 is responsible for sperm abnormalities, which lead to an inability to father children (infertility) in affected males. Researchers are working to determine how the loss of additional genes in the deleted region affects people with sensorineural deafness and male infertility.

other chromosomal conditions

Other changes in the number or structure of chromosome 15 can cause intellectual disability, delayed growth and development, hypotonia, and characteristic facial features. These changes include an extra copy of part of chromosome 15 in each cell (partial trisomy 15), a missing segment of the chromosome in each cell (partial monosomy 15), and a circular structure called ring chromosome 15. A ring chromosome occurs when a chromosome breaks in two places and the ends of the chromosome arms fuse together to form a circular structure.

Is there a standard way to diagram chromosome 15?

Geneticists use diagrams called ideograms as a standard representation for chromosomes. Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope. These bands are used to describe the location of genes on each chromosome.

What is chromosome 14?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 14, one copy inherited from each parent, form one of the pairs. Chromosome 14 spans more than 107 million DNA building blocks (base pairs) and represents about 3.5 percent of the total DNA in cells.
Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 14 likely contains 800 to 900 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 14 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 14 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 14. This list of disorders associated with genes on chromosome 14 provides links to additional information.
Changes in the structure or number of copies of a chromosome can also cause problems with health and development. The following chromosomal conditions are associated with such changes in chromosome 14.

cancers

Rearrangements (translocations) of genetic material between chromosome 14 and other chromosomes have been associated with several types of cancer. These chromosome abnormalities are somatic, which means they are acquired during a person's lifetime and are present only in certain cells. Studies show that these translocations disrupt genes that are critical for keeping cell growth and division under control. Unregulated cell division can lead to the development of cancer.
Translocations involving chromosome 14 have been found in cancers of blood-forming cells (leukemias), cancers of immune system cells (lymphomas), and several related diseases. For example, Burkitt lymphoma, a cancer of white blood cells that occurs most often in children and young adults, is related to a translocation between chromosomes 8 and 14. Another type of lymphoma, called follicular lymphoma, is often associated with a translocation between chromosomes 14 and 18. In a cancer of white blood cells called multiple myeloma, the presence of a translocation between chromosomes 4 and 14 is associated with a more aggressive form of the disease.

ring chromosome 14 syndrome

Ring chromosome 14 syndrome is caused by a chromosomal abnormality known as a ring chromosome 14 or r(14). A ring chromosome is a circular structure that occurs when a chromosome breaks in two places and its broken ends fuse together. People with ring chromosome 14 syndrome have one copy of this abnormal chromosome in some or all of their cells.
Researchers believe that several critical genes near the end of the long (q) arm of chromosome 14 are lost when the ring chromosome forms. The loss of these genes is likely responsible for several of the major features of ring chromosome 14 syndrome, including intellectual disability and delayed development. Researchers are still working to determine which missing genes contribute to the signs and symptoms of this disorder.
Epilepsy is a common feature of ring chromosome syndromes, including ring chromosome 14. There may be something about the ring structure itself that causes epilepsy. Seizures may occur because certain genes on the ring chromosome 14 are less active than those on the normal chromosome 14. Alternately, seizures might result from instability of the ring chromosome in some cells.

other chromosomal conditions

A rare condition known as terminal deletion 14 syndrome causes signs and symptoms similar to those of ring chromosome 14 syndrome. Terminal deletion 14 syndrome is caused by the loss of several genes at the end (terminus) of the long (q) arm of chromosome 14. In addition, some people with terminal deletion 14 syndrome have a loss or gain of genetic material from another chromosome. People with this condition may have weak muscle tone (hypotonia), a small head (microcephaly), frequent respiratory infections, developmental delay, and learning difficulties.
Other changes in the number or structure of chromosome 14 can have a variety of effects, including delayed growth and development, distinctive facial features, and other health problems. Several different changes involving chromosome 14 have been reported. These include an extra copy of a segment of chromosome 14 in every cell (partial trisomy 14), an extra copy of the entire chromosome in only some of the body's cells (mosaic trisomy 14), and deletions or duplications of part of chromosome 14. Full trisomy 14, an extra copy of the entire chromosome 14 in all of the body's cells, is not compatible with life.
Health problems can also result from a chromosome abnormality called uniparental disomy (UPD). UPD occurs when people inherit both copies of a chromosome from one parent instead of one copy from each parent. The long arm of chromosome 14 contains some genes that are active only when inherited from the mother, and other genes that are active only when inherited from the father. Therefore, people who have two paternal copies or two maternal copies of chromosome 14 are missing some functional genes and have an extra copy of others.
When both copies of chromosome 14 are inherited from the mother, the phenomenon is known as maternal UPD 14. Maternal UPD 14 is associated with premature birth, slow growth before and after birth, short stature, developmental delay, small hands and feet, and early onset of puberty. When both copies of the chromosome are inherited from the father, the phenomenon is known as paternal UPD 14. Paternal UPD 14 is associated with an excess of amniotic fluid (which surrounds the baby before birth); an opening in the wall of the abdomen; distinctive facial features; a small, bell-shaped chest with short ribs; and developmental delay. Both maternal UPD 14 and paternal UPD 14 appear to be rare.

Is there a standard way to diagram chromosome 14?

Geneticists use diagrams called ideograms as a standard representation for chromosomes. Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope. These bands are used to describe the location of genes on each chromosome.

What is chromosome 13?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 13, one copy inherited from each parent, form one of the pairs. Chromosome 13 is made up of about 115 million DNA building blocks (base pairs) and represents between 3.5 and 4 percent of the total DNA in cells.
Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 13 likely contains 300 to 400 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 13 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 13 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 13. This list of disorders associated with genes on chromosome 13 provides links to additional information.
Changes in the structure or number of copies of a chromosome can also cause problems with health and development. The following chromosomal conditions are associated with such changes in chromosome 13.

8p11 myeloproliferative syndrome

A rearrangement (translocation) of genetic material involving chromosome 13 has been identified in most people with a rare blood cancer called 8p11 myeloproliferative syndrome. This condition is characterized by an increased number of white blood cells (myeloproliferative disorder) and the development of lymphoma, a blood-related cancer that causes tumor formation in the lymph nodes. The myeloproliferative disorder usually develops into another form of blood cancer called acute myeloid leukemia. 8p11 myeloproliferative syndrome most commonly results from a translocation between chromosome 13 and chromosome 8, written as t(8;13)(p11;q12). This genetic change fuses part of the ZMYM2 gene on chromosome 13 with part of the FGFR1 gene on chromosome 8. The translocation occurs only in cancer cells.
The protein produced from the normal FGFR1 gene can turn on cellular signaling that helps the cell respond to its environment, for example by stimulating cell growth. The protein produced from the fused ZMYM2-FGFR1 gene leads to constant FGFR1 signaling. The uncontrolled signaling promotes continuous cell growth and division, leading to cancer.

retinoblastoma

Retinoblastoma, a cancer of the light-sensing tissue at the back of the eye (the retina) that affects mostly children, is caused by abnormalities of a gene called RB1. This gene is located on a region of the long (q) arm of chromosome 13 designated 13q14. Although most retinoblastomas are caused by mutations within the RB1 gene, a small percentage of retinoblastomas result from a deletion of the 13q14 region.
In addition to retinoblastoma, deletions of the 13q14 region may cause intellectual disability, slow growth, and characteristic facial features such as prominent eyebrows, a broad nasal bridge, a short nose, and ear abnormalities. A loss of several genes is likely responsible for these developmental problems, although researchers have not determined which other genes in the deleted region are involved.

trisomy 13

Trisomy 13 occurs when each cell in the body has three copies of chromosome 13 instead of the usual two copies. Trisomy 13 can also result from an extra copy of chromosome 13 in only some of the body's cells (mosaic trisomy 13).
In some cases, trisomy 13 occurs when part of chromosome 13 becomes attached (translocated) to another chromosome during the formation of reproductive cells (eggs and sperm) or very early in embryonic development. Affected individuals have two copies of chromosome 13, plus extra material from chromosome 13 attached to another chromosome. People with this genetic change are said to have translocation trisomy 13. The physical signs of translocation trisomy 13 may be different from those typically seen in trisomy 13 because only part of chromosome 13 is present in three copies.
Researchers believe that extra copies of some genes on chromosome 13 disrupt the course of normal development, causing the characteristic features of trisomy 13 and the increased risk of medical problems associated with this disorder.

other cancers

Changes in chromosome 13 have been associated with several types of cancer. These genetic changes are somatic, which means they are acquired during a person's lifetime and are present only in certain cells. The loss of genetic material from the middle of chromosome 13 is common in cancers of blood-forming cells (leukemias), cancers of immune system cells (lymphomas), and other related cancers.

other chromosomal conditions

Partial monosomy and partial trisomy of chromosome 13 occur when a portion of the long (q) arm of this chromosome is deleted or duplicated, respectively. The effect of missing or extra chromosome material varies with the size and location of the chromosome abnormality. Affected individuals may have developmental delay, intellectual disability, low birth weight, and other physical abnormalities.

Is there a standard way to diagram chromosome 13?

Geneticists use diagrams called ideograms as a standard representation for chromosomes. Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope. These bands are used to describe the location of genes on each chromosome.

What is chromosome 12?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 12, one copy inherited from each parent, form one of the pairs. Chromosome 12 spans almost 134 million DNA building blocks (base pairs) and represents between 4 and 4.5 percent of the total DNA in cells.
Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 12 likely contains 1,100 to 1,200 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 12 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 12 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 12. This list of disorders associated with genes on chromosome 12 provides links to additional information.
Changes in the structure or number of copies of a chromosome can also cause problems with health and development. The following chromosomal conditions are associated with such changes in chromosome 12.

cancers

Changes in chromosome 12 have been identified in several types of cancer. These genetic changes are somatic, which means they are acquired during a person's lifetime and are present only in certain cells. For example, rearrangements (translocations) of genetic material between chromosome 12 and other chromosomes are often found in certain cancers of blood-forming cells (leukemias) and cancers of immune system cells (lymphomas). Additionally, somatic mutations may lead to an extra copy of chromosome 12 (trisomy 12) in cancer cells, specifically a type of leukemia called chronic lymphocytic leukemia.
Translocations involving chromosome 12 have also been found in solid tumors such as lipomas and liposarcomas, which are made up of fatty tissue. In these tumors, the most common chromosome 12 rearrangements involve the long (q) arm in a region designated q13-q15. Abnormalities of chromosome 12 have been identified in at least two other rare tumors, angiomatoid fibrous histiocytomas and clear cell sarcomas. Angiomatoid fibrous histiocytomas occur primarily in adolescents and young adults and are usually found in the arms and legs (extremities). Clear cell sarcomas occur most often in young adults and tend to be associated with tendons and related structures called aponeuroses.
Researchers are working to determine which genes on chromosome 12 are disrupted by translocations, and they are studying how these chromosomal changes could contribute to the uncontrolled growth and division of tumor cells.

Pallister-Killian mosaic syndrome

Pallister-Killian mosaic syndrome is usually caused by the presence of an abnormal extra chromosome called an isochromosome 12p or i(12p). An isochromosome is a chromosome with two identical arms. Normal chromosomes have one long (q) arm and one short (p) arm, but isochromosomes have either two q arms or two p arms. Isochromosome 12p is a version of chromosome 12 made up of two p arms.
Cells normally have two copies of each chromosome, one inherited from each parent. In people with Pallister-Killian mosaic syndrome, cells have the two usual copies of chromosome 12, but some cells also have the isochromosome 12p. These cells have a total of four copies of all the genes on the p arm of chromosome 12. The extra genetic material from the isochromosome disrupts the normal course of development, causing the characteristic features of this disorder.
Although Pallister-Killian mosaic syndrome is usually caused by an isochromosome 12p, other, more complex chromosomal changes involving chromosome 12 are responsible for the disorder in rare cases.

PDGFRB-associated chronic eosinophilic leukemia

Translocations involving chromosome 12 are involved in a type of blood cell cancer called PDGFRB-associated chronic eosinophilic leukemia. This condition is characterized by an increased number of eosinophils, a type of white blood cell. The most common translocation that causes this condition fuses part of the PDGFRB gene from chromosome 5 with part of the ETV6 gene from chromosome 12, written as t(5;12)(q31-33;p13). Translocations that fuse the PDGFRB gene with other genes can also cause PDGFRB-associated chronic eosinophilic leukemia, but these translocations are relatively uncommon. These translocations are acquired during a person's lifetime and are present only in cancer cells. This type of genetic change, called a somatic mutation, is not inherited.
The protein produced from the ETV6-PDGFRB fusion gene, called ETV6/PDGFRβ, functions differently than the proteins normally produced from the individual genes. The ETV6 protein normally turns off (represses) gene activity and the PDGFRβ protein plays a role in turning on (activating) signaling pathways. The ETV6/PDGFRβ protein is always turned on, activating signaling pathways and gene activity. When the ETV6-PDGFRB fusion gene mutation occurs in cells that develop into blood cells, the growth of eosinophils (and occasionally other white blood cells, such as neutrophils and mast cells) is poorly controlled, leading to PDGFRB-associated chronic eosinophilic leukemia. It is unclear why eosinophils are preferentially affected by this genetic change.

other chromosomal conditions

Other changes in the number or structure of chromosome 12 can have a variety of effects on health and development. These effects include intellectual disability, slow growth, distinctive facial features, weak muscle tone (hypotonia), skeletal abnormalities, and heart defects.
Several different changes involving chromosome 12 have been reported, including an extra piece of the chromosome in each cell (partial trisomy 12), a missing segment of the chromosome in each cell (partial monosomy 12), and a circular structure called a ring chromosome 12. Ring chromosomes occur when a chromosome breaks in two places and the ends of the chromosome arms fuse together to form a circular structure.

Is there a standard way to diagram chromosome 12?

Geneticists use diagrams called ideograms as a standard representation for chromosomes. Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope. These bands are used to describe the location of genes on each chromosome.

What is chromosome 11?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 11, one copy inherited from each parent, form one of the pairs. Chromosome 11 spans about 135 million DNA building blocks (base pairs) and represents between 4 and 4.5 percent of the total DNA in cells.
Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 11 likely contains 1,300 to 1,400 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 11 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 11 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 11. This list of disorders associated with genes on chromosome 11 provides links to additional information.
Changes in the structure or number of copies of a chromosome can also cause problems with health and development. The following chromosomal conditions are associated with such changes in chromosome 11.

Beckwith-Wiedemann syndrome

Beckwith-Wiedemann syndrome results from the abnormal regulation of genes on part of the short (p) arm of chromosome 11. The genes are located close together in a region designated 11p15.5 near one end of the chromosome.
People normally inherit one copy of chromosome 11 from each parent. For most genes on this chromosome, both copies of the gene are expressed, or "turned on," in cells. For some genes in the 11p15.5 region, however, only the copy inherited from a person's father (the paternal copy) is expressed. For other genes, only the copy inherited from a person's mother (the maternal copy) is expressed. These parent-specific differences in gene expression are caused by a phenomenon called genomic imprinting. Researchers have determined that changes in genomic imprinting disrupt the regulation of several genes located at 11p15.5, including CDKN1C, H19, IGF2, and KCNQ1OT1. Because these genes are involved in directing normal growth, problems with their regulation lead to overgrowth and the other characteristic features of Beckwith-Wiedemann syndrome.
Ten percent to 20 percent of cases of Beckwith-Wiedemann syndrome are caused by a genetic change known as paternal uniparental disomy (UPD). Paternal UPD causes people to have two active copies of paternally expressed imprinted genes rather than one active copy from the father and one inactive copy from the mother. People with paternal UPD are also missing genes that are active only on the maternal copy of the chromosome. In Beckwith-Wiedemann syndrome, paternal UPD usually occurs early in embryonic development and affects only some of the body's cells. This phenomenon is called mosaicism. Mosaic paternal UPD leads to an imbalance in active paternal and maternal genes on chromosome 11, which underlies the signs and symptoms of the disorder.
About 1 percent of all people with Beckwith-Wiedemann syndrome have a chromosomal abnormality such as a rearrangement (translocation) involving 11p15.5 or abnormal copying (duplication) of genetic material in this region. Like the other genetic changes responsible for Beckwith-Wiedemann syndrome, these changes disrupt the normal regulation of genes in this part of chromosome 11.

Emanuel syndrome

Emanuel syndrome is caused by the presence of extra genetic material from chromosome 11 and chromosome 22 in each cell. In addition to the usual 46 chromosomes, people with Emanuel syndrome have an extra (supernumerary) chromosome consisting of a piece of chromosome 22 attached to a piece of chromosome 11. The extra chromosome is known as a derivative 22 or der(22) chromosome.
People with Emanuel syndrome typically inherit the der(22) chromosome from an unaffected parent. The parent carries a chromosomal rearrangement between chromosomes 11 and 22 called a balanced translocation. No genetic material is gained or lost in a balanced translocation, so these chromosomal changes usually do not cause any health problems. As the translocation is passed to the next generation, it can become unbalanced. Individuals with Emanuel syndrome inherit an unbalanced translocation between chromosomes 11 and 22 in the form of a der(22) chromosome. These individuals have two normal copies of chromosome 11, two normal copies of chromosome 22, and extra genetic material from the der(22) chromosome.
As a result of the extra chromosome, people with Emanuel syndrome have three copies of some genes in each cell instead of the usual two copies. The excess genetic material disrupts the normal course of development, leading to intellectual disability and birth defects. Researchers are working to determine which genes are included on the der(22) chromosome and what role these genes play in development.

Ewing sarcoma

A translocation involving chromosome 11 can cause a type of cancerous tumor known as Ewing sarcoma. These tumors develop in bones or soft tissues, such as nerves and cartilage. This translocation, t(11;22), fuses part of the EWSR1 gene from chromosome 22 with part of the FLI1 gene from chromosome 11, creating the EWSR1/FLI1 fusion gene. This mutation is acquired during a person's lifetime and is present only in tumor cells. This type of genetic change, called a somatic mutation, is not inherited.
The protein produced from the EWSR1/FLI1 fusion gene, called EWS/FLI, has functions of the protein products of both genes. The FLI protein, produced from the FLI1 gene, attaches (binds) to DNA and regulates an activity called transcription, which is the first step in the production of proteins from genes. The FLI protein controls the growth and development of some cell types by regulating the transcription of certain genes. The EWS protein, produced from the EWSR1 gene, also regulates transcription. The EWS/FLI protein has the DNA-binding function of the FLI protein as well as the transcription regulation function of the EWS protein. It is thought that the EWS/FLI protein turns the transcription of a variety of genes on and off abnormally. This dysregulation of transcription leads to uncontrolled growth and division (proliferation) and abnormal maturation and survival of cells, causing tumor development.

Jacobsen syndrome

Jacobsen syndrome, which is also known as 11q terminal deletion disorder, is caused by a deletion of genetic material at the end (terminus) of the long (q) arm of chromosome 11. The size of the deletion varies among affected individuals, with most affected people missing from about 5 million to 16 million DNA building blocks (also written as 5 Mb to 16 Mb). In almost all affected people, the deletion includes the tip of chromosome 11. Larger deletions tend to cause more severe signs and symptoms than smaller deletions.
The features of Jacobsen syndrome are likely related to the loss of multiple genes on chromosome 11. Depending on its size, the deleted region can contain from about 170 to more than 340 genes. Many of these genes have not been well characterized. However, genes in this region appear to be critical for the normal development of many parts of the body, including the brain, facial features, and heart. Researchers are working to determine which genes contribute to the specific features of Jacobsen syndrome.

neuroblastoma

About 35 percent of people with neuroblastoma have a deletion of genetic material on the long (q) arm of chromosome 11 at a position designated 11q23. Neuroblastoma is a type of cancerous tumor composed of immature nerve cells (neuroblasts). The 11q23 deletion can occur in the body's cells after conception, which is called a somatic mutation, or it can be inherited from a parent. This deletion is associated with a more severe form of neuroblastoma. Researchers believe the deleted region could contain a gene that keeps cells from growing and dividing too quickly or in an uncontrolled way, called a tumor suppressor gene. When tumor suppressor genes are deleted, cancer can occur. However, no tumor suppressor genes have been identified in the deleted region of chromosome 11. It is unknown how deletion of this region contributes to the formation or progression of neuroblastoma.

Potocki-Shaffer syndrome

A condition called Potocki-Shaffer syndrome is caused by the deletion of a segment of the short (p) arm of chromosome 11 at a position described as 11p11.2. This condition is also known as proximal 11p deletion syndrome. The characteristic features of Potocki-Shaffer syndrome include enlarged openings in the two bones that make up much of the top and sides of the skull (enlarged parietal foramina), multiple noncancerous bone tumors called exostoses, intellectual disability, delayed development, a distinctive facial appearance, and problems with vision. Occasionally, people with this condition have defects in the heart, kidneys, and urinary tract. The features of Potocki-Shaffer syndrome result from the loss of several genes on the short arm of chromosome 11. In particular, the deletion of a gene called ALX4 causes enlarged parietal foramina in people with this condition, while the loss of another gene, EXT2, underlies the multiple exostoses. Researchers are working to find genes on the short arm of chromosome 11 that are associated with the other features of Potocki-Shaffer syndrome.
Another condition called WAGR syndrome (described below) is caused by a deletion of genetic material from the short arm of chromosome 11 at a position described as 11p13. Occasionally, a deletion is large enough to include the 11p11.2 and 11p13 regions. Individuals with such a deletion have signs and symptoms of both Potocki-Shaffer syndrome and WAGR syndrome.

Russell-Silver syndrome

Like Beckwith-Wiedemann syndrome, Russell-Silver syndrome can result from changes in genes in the 11p15.5 region. Specifically, Russell-Silver syndrome has been associated with changes in genomic imprinting that affect the regulation of the H19 and IGF2 genes on chromosome 11. The changes are different from those seen in Beckwith-Wiedemann syndrome and have the opposite effect on growth. Although both disorders can be caused by abnormal regulation of these genes, the changes that cause Russell-Silver syndrome lead to slow growth and short stature instead of overgrowth.

Wilms tumor, aniridia, genitourinary anomalies, and mental retardation syndrome

Wilms tumor, aniridia, genitourinary anomalies, and mental retardation syndrome, more commonly known by the acronym WAGR syndrome, is caused by a deletion of genetic material on the short (p) arm of chromosome 11 at a position described as 11p13. The signs and symptoms of WAGR syndrome are related to the loss of multiple genes from this part of the chromosome. The size of the deletion varies among affected individuals. Researchers have identified genes on the short arm of chromosome 11 that are associated with particular features of WAGR syndrome. A loss of the PAX6 gene disrupts normal eye development, leading to aniridia and other eye problems, and may also affect the development of the brain. Deletion of the WT1 gene is responsible for the genitourinary abnormalities and the increased risk of Wilms tumor (a rare form of kidney cancer) in affected individuals. Researchers are working to identify additional genes deleted in people with WAGR syndrome and determine how their loss leads to the other features of the disorder.

other cancers

Changes in chromosome 11 have been identified in other types of cancer. These chromosomal changes are somatic, which means they are acquired during a person's lifetime and are present only in certain cells. In some cases, translocations of genetic material between chromosome 11 and other chromosomes have been associated with cancers of blood-forming cells (leukemias) and cancers of immune system cells (lymphomas).

other chromosomal conditions

Other changes in the number or structure of chromosome 11 can have a variety of effects, including intellectual disability, delayed development, slow growth, distinctive facial features, and weak muscle tone (hypotonia). Changes involving chromosome 11 include an extra piece of the chromosome in each cell (partial trisomy 11), a missing segment of the chromosome in each cell (partial monosomy 11), and a circular structure called a ring chromosome 11. Ring chromosomes occur when a chromosome breaks in two places and the ends of the chromosome arms fuse together to form a circular structure.

Is there a standard way to diagram chromosome 11?

Geneticists use diagrams called ideograms as a standard representation for chromosomes. Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope. These bands are used to describe the location of genes on each chromosome.

What is chromosome 10?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 10, one copy inherited from each parent, form one of the pairs. Chromosome 10 spans more than 135 million DNA building blocks (base pairs) and represents between 4 and 4.5 percent of the total DNA in cells.
Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 10 likely contains 700 to 800 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 10 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 10 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 10. This list of disorders associated with genes on chromosome 10 provides links to additional information.
Changes in the structure or number of copies of a chromosome can also cause problems with health and development. The following chromosomal conditions are associated with such changes in chromosome 10.

cancers

Changes in the number and structure of chromosome 10 are associated with several types of cancer. For example, a loss of all or part of chromosome 10 is often found in brain tumors called gliomas, particularly in aggressive, fast-growing gliomas. The association of cancerous tumors with a loss of chromosome 10 suggests that some genes on this chromosome play critical roles in controlling the growth and division of cells. Without these genes, cells could grow and divide too quickly or in an uncontrolled way, resulting in cancer. Researchers are working to identify the specific genes on chromosome 10 that may be involved in the development and progression of gliomas.
A complex rearrangement (translocation) of genetic material between chromosomes 10 and 11 is associated with several types of blood cancer known as leukemias. This chromosomal abnormality is found only in cancer cells. It fuses part of a specific gene from chromosome 11 (the MLL gene) with part of another gene from chromosome 10 (the MLLT10 gene). The abnormal protein produced from this fused gene signals cells to divide without control or order, leading to the development of cancer.

Crohn disease

Variations in a particular region of chromosome 10 have been associated with the risk of developing Crohn disease. These genetic changes are located on the long (q) arm of the chromosome at a position designated 10q21.1. Researchers refer to this part of chromosome 10 as a "gene desert" because it contains no known genes. However, it may contain stretches of DNA that help regulate nearby genes such as ERG2. This gene has a potential role in immune system function, and researchers are interested in studying the gene further to determine whether it is associated with Crohn disease risk.

other chromosomal conditions

Other changes in the number or structure of chromosome 10 can have a variety of effects. Intellectual disability, delayed growth and development, distinctive facial features, and heart defects are common features. Changes to chromosome 10 include an extra piece of the chromosome in each cell (partial trisomy), a missing segment of the chromosome in each cell (partial monosomy), and an abnormal structure called a ring chromosome 10. Ring chromosomes occur when a chromosome breaks in two places and the ends of the chromosome arms fuse together to form a circular structure. Rearrangements (translocations) of genetic material between chromosomes can also lead to extra or missing material from chromosome 10.

Is there a standard way to diagram chromosome 10?

Geneticists use diagrams called ideograms as a standard representation for chromosomes. Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope. These bands are used to describe the location of genes on each chromosome.

What is chromosome 9?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 9, one copy inherited from each parent, form one of the pairs. Chromosome 9 is made up of about 141 million DNA building blocks (base pairs) and represents approximately 4.5 percent of the total DNA in cells.
Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 9 likely contains 800 to 900 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 9 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 9 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 9. This list of disorders associated with genes on chromosome 9 provides links to additional information.
Changes in the structure or number of copies of a chromosome can also cause problems with health and development. The following chromosomal conditions are associated with such changes in chromosome 9.

bladder cancer

Deletions of part or all of chromosome 9 are commonly found in bladder cancers. These chromosomal changes are seen only in cancer cells and typically occur early in tumor formation. Researchers believe that several genes that play a role in bladder cancer may be located on chromosome 9. They suspect that these genes may be tumor suppressors, which means they normally help prevent cells from growing and dividing in an uncontrolled way. Researchers are working to determine which genes, when altered or missing, are involved in the development and progression of bladder tumors.

Kleefstra syndrome

Most people with Kleefstra syndrome, a disorder with signs and symptoms involving many parts of the body, are missing a sequence of about 1 million DNA building blocks (base pairs) on one copy of chromosome 9 in each cell. The deletion occurs near the end of the long (q) arm of the chromosome at a location designated q34.3, a region containing a gene called EHMT1. Some affected individuals have shorter or longer deletions in the same region.
The loss of the EHMT1 gene from one copy of chromosome 9 in each cell is believed to be responsible for the characteristic features of Kleefstra syndrome in people with the 9q34.3 deletion. However, the loss of other genes in the same region may lead to additional health problems in some affected individuals.
The EHMT1 gene provides instructions for making an enzyme called euchromatic histone methyltransferase 1. Histone methyltransferases are enzymes that modify proteins called histones. Histones are structural proteins that attach (bind) to DNA and give chromosomes their shape. By adding a molecule called a methyl group to histones, histone methyltransferases can turn off (suppress) the activity of certain genes, which is essential for normal development and function. A lack of euchromatic histone methyltransferase 1 enzyme impairs proper control of the activity of certain genes in many of the body's organs and tissues, resulting in the abnormalities of development and function characteristic of Kleefstra syndrome.

9q22.3 microdeletion

9q22.3 microdeletion is a chromosomal change in which a small piece of the long (q) arm of chromosome 9 is deleted in each cell. Affected individuals are missing at least 352,000 base pairs, also written as 352 kilobases (kb), in the q22.3 region of chromosome 9. This 352-kb segment is known as the minimum critical region because it is the smallest deletion that has been found to cause the signs and symptoms related to 9q22.3 microdeletions. These signs and symptoms include delayed development, intellectual disability, certain physical abnormalities, and the characteristic features of a genetic condition called Gorlin syndrome (also known as nevoid basal cell carcinoma syndrome). 9q22.3 microdeletions can also be much larger; the largest reported deletion included 20.5 million base pairs (20.5 Mb).
People with a 9q22.3 microdeletion are missing from two to more than 270 genes on chromosome 9. All known 9q22.3 microdeletions include the PTCH1 gene. Researchers believe that many of the features associated with 9q22.3 microdeletions, particularly the signs and symptoms of Gorlin syndrome, result from a loss of the PTCH1 gene. Other signs and symptoms related to 9q22.3 microdeletions probably result from the loss of additional genes in the q22.3 region. Researchers are working to determine which missing genes contribute to the other features associated with the deletion.

other cancers

Changes in the structure of chromosome 9 have been found in many types of cancer. These changes, which occur only in cancer cells, usually involve a loss of part of the chromosome or a rearrangement of chromosomal material. For example, a loss of part of the long (q) arm of chromosome 9 has been identified in some types of brain tumor. It is unclear how these chromosomal changes are related to the development and growth of cancers.
A rearrangement (translocation) of genetic material between chromosomes 9 and 22 is associated with several types of blood cancer known as leukemias. This chromosomal abnormality, which is commonly called the Philadelphia chromosome, is found only in cancer cells. It fuses part of a specific gene from chromosome 22 (the BCR gene) with part of another gene from chromosome 9 (the ABL1 gene). The protein produced from these fused genes signals tumor cells to continue dividing abnormally and prevents them from adequately repairing DNA damage.
The Philadelphia chromosome has been identified in most cases of a slowly progressing form of blood cancer called chronic myeloid leukemia (CML). It also has been found in some cases of more rapidly progressing blood cancers known as acute leukemias. The presence of the Philadelphia chromosome can help predict how a cancer will progress and provides a target for molecular therapies.

other chromosomal conditions

Other changes in the structure or number of copies of chromosome 9 can have a variety of effects. Intellectual disability, delayed development, distinctive facial features, and an unusual head shape are common features. Changes to chromosome 9 include an extra piece of the chromosome in each cell (partial trisomy), a missing segment of the chromosome in each cell (partial monosomy), and a circular structure called a ring chromosome 9. A ring chromosome occurs when both ends of a broken chromosome are reunited. Rearrangements (translocations) of genetic material between chromosome 9 and other chromosomes can also lead to extra or missing chromosome segments.

Is there a standard way to diagram chromosome 9?

Geneticists use diagrams called ideograms as a standard representation for chromosomes. Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope. These bands are used to describe the location of genes on each chromosome.

What is chromosome 8?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 8, one copy inherited from each parent, form one of the pairs. Chromosome 8 spans more than 146 million DNA building blocks (base pairs) and represents between 4.5 and 5 percent of the total DNA in cells.
Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 8 likely contains about 700 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 8 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 8 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 8. This list of disorders associated with genes on chromosome 8 provides links to additional information.
Changes in the structure or number of copies of a chromosome can also cause problems with health and development. The following chromosomal conditions are associated with such changes in chromosome 8.

Langer-Giedion syndrome

Langer-Giedion syndrome is caused by a deletion or mutation in several genes on the long (q) arm of chromosome 8 at a position described as 8q24.1. This condition causes bone abnormalities, including noncancerous bone tumors known as exostoses, and distinctive facial features. The signs and symptoms of this condition are related to the deletion or mutation in at least two genes from this part of the chromosome. Researchers have determined that the loss of a functional EXT1 gene is responsible for the multiple noncancerous (benign) bone tumors called exostoses seen in people with Langer-Giedion syndrome. Loss of a functional TRPS1 gene may cause the other bone and facial abnormalities. One copy of the EXT1 gene and the TRPS1 gene are always missing or mutated in affected individuals; however, neighboring genes may also be involved. The loss of additional genes from this region of chromosome 8 likely contributes to the varied features of Langer-Giedion syndrome.

8p11 myeloproliferative syndrome

Translocations of genetic material between chromosome 8 and other chromosomes can cause 8p11 myeloproliferative syndrome. This condition is characterized by an increased number of white blood cells (myeloproliferative disorder) and the development of lymphoma, a blood-related cancer that causes tumor formation in the lymph nodes. The myeloproliferative disorder usually develops into another form of blood cancer called acute myeloid leukemia. The most common translocation involved in this condition, written as t(8;13)(p11;q12), fuses part of the FGFR1 gene on chromosome 8 with part of the ZMYM2 gene on chromosome 13. The translocations are found only in cancer cells.
The protein produced from the normal FGFR1 gene can turn on cellular signaling that helps the cell respond to its environment, for example by stimulating cell growth. The protein produced from the fused gene, regardless of the partner gene involved, leads to constant FGFR1 signaling. The uncontrolled signaling promotes continuous cell growth and division, leading to cancer.

recombinant 8 syndrome

A rearrangement of chromosome 8 causes recombinant 8 syndrome, a condition that involves heart and urinary tract abnormalities, moderate to severe intellectual disability, and a distinctive facial appearance. This rearrangement results in a deletion of a piece of the short (p) arm and a duplication of a piece of the long (q) arm. This chromosome abnormality is written rec(8)dup(8q)inv(8)(p23.1q22.1). The signs and symptoms of recombinant 8 syndrome are related to the loss of genetic material on the short arm of chromosome 8 and the presence of extra genetic material on the long arm of chromosome 8. Researchers are working to determine which genes are involved in the deletion and duplication on chromosome 8.

other cancers

Translocations between chromosome 8 and other chromosomes have been associated with other types of cancer. For example, Burkitt lymphoma (a cancer of white blood cells called B cells that occurs most often in children and young adults) can be caused by a translocation between chromosomes 8 and 14. This translocation, written t(8;14)(q24;q32), leads to continuous cell division without control or order, which likely contributes to the development of Burkitt lymphoma. Less frequently, Burkitt lymphoma can be caused by translocations between chromosomes 8 and 2 or chromosomes 8 and 22.

other chromosomal conditions

Trisomy 8 occurs when cells have three copies of chromosome 8 instead of the usual two copies. Full trisomy 8, which occurs when all of the body's cells contain an extra copy of chromosome 8, is not compatible with life. A similar but less severe condition called mosaic trisomy 8 occurs when only some of the body's cells have an extra copy of chromosome 8. The signs and symptoms of mosaic trisomy 8 vary widely and can include intellectual disability, absence of the tissue connecting the left and right halves of the brain (corpus callosum), skeletal defects, heart problems, kidney and liver malformations, and facial abnormalities. Trisomy 8 mosaicism is also associated with an increased risk of a specific type of cancer of blood-forming cells called acute myelogenous leukemia.
Another chromosomal condition called inversion duplication 8p is caused by a rearrangement of genetic material on the short (p) arm of chromosome 8. This rearrangement results in an abnormal duplication and an inversion of a segment of the chromosome. An inversion involves the breakage of a chromosome in two places; the resulting piece of DNA is reversed and reinserted into the chromosome. People with inversion duplication 8p typically have severe intellectual disability, a thin or absent corpus callosum, weak muscle tone (hypotonia), abnormal curvature of the spine (scoliosis), and minor facial abnormalities. Some individuals with this condition may also have heart defects, underdeveloped kidneys, or eye abnormalities. Older individuals usually develop abnormal muscle stiffness (spasticity). The signs and symptoms of inversion duplication 8p tend to depend on the size and location of the chromosome segment involved. For example, inclusion of chromosome region 8p21 is thought to be associated with more severe symptoms.

Is there a standard way to diagram chromosome 8?

Geneticists use diagrams called ideograms as a standard representation for chromosomes. Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope. These bands are used to describe the location of genes on each chromosome.

What is chromosome 7?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 7, one copy inherited from each parent, form one of the pairs. Chromosome 7 spans about 159 million DNA building blocks (base pairs) and represents more than 5 percent of the total DNA in cells.
Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 7 likely contains 900 to 1,000 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 7 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 7 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 7. This list of disorders associated with genes on chromosome 7 provides links to additional information.
Changes in the structure or number of copies of a chromosome can also cause problems with health and development. The following chromosomal conditions are associated with such changes in chromosome 7.

cancers

Changes in the number or structure of chromosome 7 occur frequently in human cancers. These changes are typically somatic, which means they are acquired during a person's lifetime and are present only in tumor cells. Many forms of cancer are associated with damage to chromosome 7. In particular, changes in this chromosome have been identified in cancers of blood-forming tissue (leukemias) and cancers of immune system cells (lymphomas). A loss of part or all of one copy of chromosome 7 is common in myelodysplastic syndrome, which is a disease of the blood and bone marrow. People with this disorder have an increased risk of developing leukemia.
Studies suggest that some genes on chromosome 7 may play critical roles in controlling the growth and division of cells. Without these genes, cells could grow and divide too quickly or in an uncontrolled way, resulting in a cancerous tumor. Researchers are working to identify the genes on chromosome 7 that are involved in the development and progression of cancer.

Greig cephalopolysyndactyly syndrome

Abnormalities of chromosome 7 are responsible for some cases of Greig cephalopolysyndactyly syndrome. These chromosomal changes involve a region of the short (p) arm of chromosome 7 that contains the GLI3 gene. This gene plays an important role in the development of many tissues and organs before birth.
In some cases, Greig cephalopolysyndactyly syndrome results from a rearrangement (translocation) of genetic material between chromosome 7 and another chromosome. Other cases are caused by the deletion of several genes, including GLI3, from the short arm of chromosome 7. The loss of multiple genes can cause a more severe form of this disorder called Greig cephalopolysyndactyly contiguous gene deletion syndrome. People with this form of the disorder have characteristic developmental problems involving the limbs, head, and face along with seizures, developmental delay, and intellectual disability.

Russell-Silver syndrome

People normally inherit one copy of each chromosome from their mother and one copy from their father. For most genes, both copies are expressed, or "turned on," in cells. For some genes, however, only the copy inherited from a person's father (the paternal copy) is expressed. For other genes, only the copy inherited from a person's mother (the maternal copy) is expressed. These parent-specific differences in gene expression are caused by a phenomenon called genomic imprinting. Chromosome 7 contains a group of genes that normally undergo genomic imprinting. Abnormalities involving these genes appear to be responsible for many cases of Russell-Silver syndrome.
In 7 percent to 10 percent of cases of Russell-Silver syndrome, people inherit both copies of chromosome 7 from their mother instead of one copy from each parent. This phenomenon is called maternal uniparental disomy (UPD). Maternal UPD causes people to have two active copies of maternally expressed imprinted genes rather than one active copy from the mother and one inactive copy from the father. These individuals do not have a paternal copy of chromosome 7 and therefore do not have any copies of genes that are active only on the paternal copy. In cases of Russell-Silver syndrome caused by maternal UPD, an imbalance in active paternal and maternal genes on chromosome 7 underlies the signs and symptoms of the disorder.

Saethre-Chotzen syndrome

Some cases of Saethre-Chotzen syndrome result from abnormalities of chromosome 7. These chromosomal changes involve a region of the short (p) arm of chromosome 7 that contains the TWIST1 gene. This gene plays an important role in early development of the head, face, and limbs.
The chromosome abnormalities responsible for Saethre-Chotzen syndrome include translocations of genetic material between chromosome 7 and another chromosome, a rearrangement of genetic material within chromosome 7 (an inversion), or the formation of an abnormal circular structure called a ring chromosome 7. Each of these chromosomal changes alters or deletes the TWIST1 gene and may also affect nearby genes.
When Saethre-Chotzen syndrome is caused by a chromosomal deletion instead of a mutation within the TWIST1 gene, affected children are much more likely to have intellectual disability, developmental delay, and learning difficulties. These features are typically not seen in classic cases of Saethre-Chotzen syndrome. Researchers believe that a loss of other genes on the short arm of chromosome 7 may be responsible for these additional features.

Williams syndrome

Williams syndrome is caused by the deletion of genetic material from a portion of the long (q) arm of chromosome 7. The deleted region, which is located at position 11.23 (written as 7q11.23), is designated the Williams-Beuren region. This region includes more than 25 genes, and researchers believe that the characteristic features of Williams syndrome are probably related to the loss of several of these genes.
While a few of the specific genes related to Williams syndrome have been identified, the relationship between most of the genes in the deleted region and the signs and symptoms of Williams syndrome is unknown.

other chromosomal conditions

Whereas Williams syndrome is caused by a deletion of genes in the Williams-Beuren region of chromosome 7, another syndrome is caused by the abnormal duplication (copying) of genes in this region. This duplication appears to be associated with delayed expressive language skills (vocabulary and the production of speech) and delayed development. Very few people with a duplication of the Williams-Beuren region have been identified.
Other changes in the number or structure of chromosome 7 can cause delayed growth and development, intellectual disability, distinctive facial features, skeletal abnormalities, delayed speech, and other medical problems. Changes in chromosome 7 include an extra copy of some genetic material from this chromosome in each cell (partial trisomy 7) or a missing segment of the chromosome in each cell (partial monosomy 7). In some cases, several DNA building blocks (nucleotides) are abnormally deleted or duplicated in part of chromosome 7. A circular structure called ring chromosome 7 is also possible. Ring chromosomes occur when a chromosome breaks in two places and the ends of the chromosome arms fuse together to form a circular structure.

Is there a standard way to diagram chromosome 7?

Geneticists use diagrams called ideograms as a standard representation for chromosomes. Ideograms show a chromosome's relative size and its banding pattern. A banding pattern is the characteristic pattern of dark and light bands that appears when a chromosome is stained with a chemical solution and then viewed under a microscope. These bands are used to describe the location of genes on each chromosome.