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.

What is chromosome 6?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 6, one copy inherited from each parent, form one of the pairs. Chromosome 6 spans about 171 million DNA building blocks (base pairs) and represents between 5.5 and 6 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 6 likely contains 1,000 to 1,100 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 6 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 6 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 6. This list of disorders associated with genes on chromosome 6 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 6.

cancers

Duplications of genetic material in the short (p) arm of chromosome 6 have been associated with the growth and spread of several types of cancer. These duplications are somatic, which means they are acquired during a person's lifetime and are present only in certain cells. Researchers believe that some of the genes in the duplicated region on chromosome 6p are oncogenes. Oncogenes play roles in several critical cell functions, including cell division, the maturation of cells to carry out specific functions (cell differentiation), and the self-destruction of cells (apoptosis). When mutated, oncogenes have the potential to cause normal cells to become cancerous. The presence of extra copies of the oncogenes may allow cells to grow and divide in an uncontrolled way, leading to the progression and spread of cancer.

6q24-related transient neonatal diabetes mellitus

6q24-related transient neonatal diabetes mellitus, a type of diabetes that occurs in infants, is caused by the overactivity (overexpression) of certain genes in a region of the long (q) arm of chromosome 6 called 6q24. People inherit two copies of their genes, one from their mother and one from their father. Usually both copies of each gene are active, or "turned on," in cells. In some cases, however, only one of the two copies is normally turned on. Which copy is active depends on the parent of origin: some genes are normally active only when they are inherited from a person's father; others are active only when inherited from a person's mother. This phenomenon is known as genomic imprinting.
The 6q24 region includes paternally expressed imprinted genes, which means that normally only the copy of each gene that comes from the father is active. The copy of each gene that comes from the mother is inactivated (silenced) by a mechanism called methylation.
There are three ways that overexpression of paternally expressed imprinted genes in the 6q24 region can occur. About 40 percent of cases of 6q24-related transient neonatal diabetes mellitus are caused by a genetic change known as paternal uniparental disomy (UPD) of chromosome 6. In paternal UPD, people inherit both copies of the affected chromosome from their father instead of one copy from each parent. 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.
Another 40 percent of cases of 6q24-related transient neonatal diabetes mellitus occur when the copy of chromosome 6 that comes from the father has a duplication of genetic material including the paternally expressed imprinted genes in the 6q24 region.
The third mechanism by which overexpression of genes in the 6q24 region can occur is by impaired silencing of the maternal copy of the genes (maternal hypomethylation). Approximately 20 percent of cases of 6q24-related transient neonatal diabetes mellitus are caused by maternal hypomethylation. Some people with this disorder have a genetic change in the maternal copy of the 6q24 region that prevents genes in that region from being silenced. Other affected individuals have a more generalized impairment of gene silencing involving many imprinted regions, called hypomethylation of imprinted loci (HIL). Because HIL can cause overexpression of many genes, this mechanism may account for the additional health problems that occur in some people with 6q24-related transient neonatal diabetes mellitus.
It is not well understood how overexpression of genes in the 6q24 region causes 6q24-related transient neonatal diabetes mellitus and why the condition improves after infancy. This form of diabetes is characterized by high blood sugar levels (hyperglycemia) resulting from a shortage of the hormone insulin. Insulin controls how much glucose (a type of sugar) is passed from the blood into cells for conversion to energy.
The protein produced from one gene in the 6q24 region may help control insulin secretion by beta cells in the pancreas. In addition, overexpression of this protein has been shown to stop the cycle of cell division and lead to the self-destruction of cells (apoptosis). Researchers suggest that overexpression of this gene may reduce the number of insulin-secreting beta cells or impair their function in affected individuals.
Lack of sufficient insulin results in the signs and symptoms of diabetes mellitus. In individuals with 6q24-related transient neonatal diabetes mellitus, these signs and symptoms are most likely to occur during times of physiologic stress, including the rapid growth of infancy, childhood illnesses, and pregnancy. Because insulin acts as a growth promoter during early development, a shortage of this hormone may account for the slow growth before birth (intrauterine growth retardation) seen in 6q24-related transient neonatal diabetes mellitus.

other chromosomal conditions

Other changes in the number or structure of chromosome 6 can have a variety of effects, including delayed growth and development, intellectual disability, distinctive facial features, birth defects, and other health problems. Changes to chromosome 6 may include deletions or duplications of genetic material in the short (p) or long (q) arm of the chromosome in each cell, or a circular structure called ring chromosome 6. 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 6?

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 5?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 5, one copy inherited from each parent, form one of the pairs. Chromosome 5 spans about 181 million DNA building blocks (base pairs) and represents almost 6 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 5 likely contains about 900 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 5 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 5 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 5. This list of disorders associated with genes on chromosome 5 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 5.

cancers

Changes in the structure of chromosome 5 are associated with certain forms of cancer and conditions related to cancer. These changes are typically somatic, which means they are acquired during a person's lifetime and are present only in tumor cells. Deletions in the long (q) arm of the chromosome have been identified in a form of blood cancer known as acute myeloid leukemia (AML). These deletions also frequently occur in a disorder called myelodysplastic syndrome, which is a disease of the blood and bone marrow. People with this condition have a low number of red blood cells (anemia) and an increased risk of developing AML. When MDS is associated with a specific deletion in the long arm of chromosome 5, it is known as 5q- (5q minus) syndrome.
Studies suggest that some genes on chromosome 5 play critical roles in the growth and division of cells. When segments of the chromosome are deleted, as in some cases of AML and MDS, these important genes are missing. Without these genes, cells can grow and divide too quickly and in an uncontrolled way. Researchers are working to identify the specific genes on chromosome 5 that are related to AML and MDS.

cri-du-chat syndrome

Cri-du-chat (cat's cry) syndrome is caused by a deletion of the end of the short (p) arm of chromosome 5. This chromosomal change is written as 5p- (5p minus). The signs and symptoms of cri-du-chat syndrome are probably related to the loss of multiple genes in this region. Researchers are working to determine how the loss of these genes leads to the features of the disorder. They have discovered that in people with cri-du-chat syndrome, larger deletions tend to result in more severe intellectual disability and developmental delays than smaller deletions. Researchers have also defined regions of the short arm of chromosome 5 that are associated with particular features of cri-du-chat syndrome. A specific region designated 5p15.3 is associated with a cat-like cry, and a nearby region called 5p15.2 is associated with intellectual disability, small head size (microcephaly), and distinctive facial features.

Crohn disease

Several regions of chromosome 5 have been associated with the risk of developing Crohn disease. For example, a combination of genetic variations in a region of DNA on the long (q) arm of the chromosome (5q31) has been shown to increase a person's chance of developing Crohn disease. Together, these variations are known as the inflammatory bowel disease 5 (IBD5) locus. This region of chromosome 5 contains several related genes that may influence Crohn disease risk, including SLC22A4 and SLC22A5.
Variations in a region of the short (p) arm of chromosome 5 designated 5p13.1 are also associated with Crohn disease risk. Researchers refer to this part of chromosome 5 as a "gene desert" because it contains no known genes; however, it may contain stretches of DNA that help regulate nearby genes such as PTGER4. Research studies are under way to examine a possible connection between the PTGER4 gene and Crohn disease.

PDGFRB-associated chronic eosinophilic leukemia

Translocations involving chromosome 5 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 fusing the PDGFRB gene with one of more than 20 other genes have also been found to cause PDGFRB-associated chronic eosinophilic leukemia, but these other genetic changes 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.

periventricular heterotopia

In a few cases, abnormalities in chromosome 5 have been associated with periventricular heterotopia, a disorder characterized by abnormal clumps of nerve cells (neurons) around fluid-filled cavities (ventricles) near the center of the brain. In each case, the affected individual had extra genetic material caused by an abnormal duplication of part of this chromosome. It is not known how this duplicated genetic material results in the signs and symptoms of periventricular heterotopia.

other chromosomal conditions

Other changes in the number or structure of chromosome 5 can have a variety of effects, including delayed growth and development, distinctive facial features, birth defects, and other health problems. Changes to chromosome 5 include an extra segment of the short (p) or long (q) arm of the chromosome in each cell (partial trisomy 5p or 5q), a missing segment of the long arm of the chromosome in each cell (partial monosomy 5q), and a circular structure called ring chromosome 5. 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 5?

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 4?

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 4, one copy inherited from each parent, form one of the pairs. Chromosome 4 spans about 191 million DNA building blocks (base pairs) and represents more than 6 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 4 likely contains 1,000 to 1,100 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.
Genes on chromosome 4 are among the estimated 20,000 to 25,000 total genes in the human genome.

How are changes in chromosome 4 related to health conditions?

Many genetic conditions are related to changes in particular genes on chromosome 4. This list of disorders associated with genes on chromosome 4 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 4.

cancers

Changes in chromosome 4 have been identified in several 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. For example, rearrangements (translocations) of genetic material between chromosome 4 and several other chromosomes have been associated with leukemias, which are cancers of blood-forming cells.
A specific translocation involving chromosome 4 and chromosome 14 is commonly found in multiple myeloma, which is a cancer that starts in cells of the bone marrow. The translocation, which is written as t(4;14)(p16;q32), abnormally fuses the WHSC1 gene on chromosome 4 with part of another gene on chromosome 14. The fusion of these genes overactivates WHSC1, which appears to promote the uncontrolled growth and division of cancer cells.

facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy results from a deletion of genetic material from a region of DNA known as D4Z4. This region is located near the end of the long (q) arm of chromosome 4 at a position described as 4q35. The D4Z4 region normally consists of 11 to more than 100 repeated DNA segments, each of which is about 3,300 DNA base pairs (3.3 kb) long. However, in people with facioscapulohumeral muscular dystrophy the D4Z4 region on one copy of chromosome 4 is abnormally short, containing between 1 and 10 repeats.
It is uncertain how a shortened D4Z4 region causes the progressive muscle weakness and wasting characteristic of facioscapulohumeral muscular dystrophy. Researchers have proposed several possible mechanisms, but none have yet been proven. It appears that the D4Z4 region influences the activity of other genes located nearby on the long arm of chromosome 4. An abnormally short D4Z4 region may somehow disrupt the normal regulation of these genes. However, it is unclear which genes are influenced by D4Z4 and what role, if any, those genes play in muscle cells. Researchers suspect that genetic factors other than the shortened D4Z4 region may also be involved in facioscapulohumeral muscular dystrophy.

PDGFRA-associated chronic eosinophilic leukemia

PDGFRA-associated chronic eosinophilic leukemia is caused by genetic abnormalities that involve the PDGFRA gene, a gene found on chromosome 4. This condition is a type of blood cell cancer characterized by an increased number of eosinophils, a type of white blood cell involved in allergic reactions.
The PDGFRA gene abnormalities are somatic mutations, which are mutations acquired during a person's lifetime that are present only in certain cells. The most common of these abnormalities is a deletion of genetic material from chromosome 4 that removes approximately 800 DNA building blocks (nucleotides) and brings together parts of two genes, FIP1L1 and PDGFRA, creating the FIP1L1-PDGFRA fusion gene. Occasionally, through mechanisms other than deletion, genes other than FIP1L1 are fused with the PDGFRA gene. Rarely, mutations that change single DNA building blocks in the PDGFRA gene (point mutations) cause this condition.
The protein produced from the FIP1L1-PDGFRA fusion gene (as well as other PDGFRA fusion genes) has the function of the PDGFRA protein, which stimulates signaling pathways inside the cell that control many important cellular processes, such as cell growth and division (proliferation) and cell survival. Unlike the normal PDGFRA protein, however, the fusion protein is constantly turned on (constitutively activated), which means the cells are always receiving signals to proliferate. Similarly, point mutations in the PDGFRA gene can result in a constitutively activated PDGFRA protein. When the FIP1L1-PDGFRA fusion gene or point mutations in the PDGFRA gene occur in blood cell precursors, the growth of eosinophils (and occasionally other blood cells) is poorly controlled, leading to PDGFRA-associated chronic eosinophilic leukemia. It is unclear why eosinophils are preferentially affected by this genetic change.

Wolf-Hirschhorn syndrome

Wolf-Hirschhorn syndrome is caused by a deletion of genetic material near the end of the short (p) arm of chromosome 4 at a position described as 4p16.3. The signs and symptoms of this condition are related to the loss of multiple genes from this part of the chromosome. The size of the deletion varies among affected individuals; studies suggest that larger deletions tend to result in more severe intellectual disability and physical abnormalities than smaller deletions.
The region of chromosome 4 that is deleted most often in people with Wolf-Hirschhorn syndrome is known as Wolf-Hirschhorn syndrome critical region 2 (WHSCR-2). This region contains several genes, some of which are known to play important roles in early development. A loss of these genes leads to developmental delay, a distinctive facial appearance, and other characteristic features of the condition. Scientists are working to identify additional genes at the end of the short arm of chromosome 4 that contribute to the characteristic features of Wolf-Hirschhorn syndrome.

other chromosomal conditions

Some deletions of genetic material from the short (p) arm of chromosome 4 do not involve the critical region WHSCR-2. These deletions cause signs and symptoms that are distinct from those of Wolf-Hirschhorn syndrome, including mild intellectual disability and, in some cases, rapid (accelerated) growth. People with this type of deletion usually do not have seizures.
Trisomy 4 occurs when cells have three copies of chromosome 4 instead of the usual two copies. Full trisomy 4, which occurs when all of the body's cells contain an extra copy of chromosome 4, is not compatible with life. A similar but somewhat less severe condition called mosaic trisomy 4 occurs when only some of the body's cells have an extra copy of chromosome 4. The signs and symptoms of mosaic trisomy 4 vary widely and can include heart defects, abnormalities of the fingers and toes, and other birth defects. Mosaic trisomy 4 is very rare; only a few cases have been reported.
Other changes in the number or structure of chromosome 4 can have a variety of effects including delayed growth and development, intellectual disability, distinctive facial features, heart defects, and other medical problems. Changes involving chromosome 4 include an extra piece of the chromosome in each cell (partial trisomy 4), a missing segment of the chromosome in each cell (partial monosomy 4), and a circular structure called a ring chromosome 4. 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 4?

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.