Chromosome 8

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.

cancers

Rearrangements (translocations) of genetic material between chromosome 8 and other chromosomes have been associated with several types of cancer. For example, Burkitt lymphoma (a cancer of white blood 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.

Langer-Giedion syndrome

Langer-Giedion syndrome is caused by a deletion or mutation of several genes on the long (q) arm of chromosome 8 at a position described as 8q24.1. 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.

recombinant 8 syndrome

Recombinant 8 syndrome is caused by a rearrangement of chromosome 8 that 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 of 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 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.

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.

See How do geneticists indicate the location of a gene? in the Handbook.

You may find the following resources about chromosome 8 helpful. These materials are written for the general public.

• Additional NIH Resources - National Institutes of Health
  National Human Genome Research Institute: Chromosome Abnormalities
• Educational resources - Information pages
  Atlas of Genetics and Cytogenetics in Oncology and Haematology
• MedlinePlus - Health information
  Encyclopedia: Chromosome

You may also be interested in these resources, which are designed for genetics professionals and researchers.

• Research Resources - Tools for researchers (5 links)
• PubMed - Recent literature
• OMIM - Genetic disorder catalog (3 links)
• Map Viewer - Genetic maps

The Handbook provides basic information about genetics in clear language.

• What is DNA?
• What is a chromosome?
• How many chromosomes do people have?
• Can changes in chromosomes affect health and development?

These links provide additional genetics resources that may be useful.

• Genetics education
• Human Genome Project
• Resources for Genetic Researchers

acute ; acute myelogenous leukemia ; base pair ; benign ; cancer ; cell ; cell division ; chromosome ; corpus callosum ; deletion ; DNA ; duplication ; exostoses ; gene ; hypotonia ; inversion ; kidney ; leukemia ; lymphoma ; malformation ; mosaic ; mosaicism ; muscle tone ; mutation ; myelogenous ; rearrangement ; scoliosis ; sign ; spasticity ; symptom ; syndrome ; tissue ; translocation ; trisomy ; tumor ; white blood cells

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.

See also Understanding Medical Terminology.