Chromosome 2

Many genetic conditions are related to changes in particular genes on chromosome 2. This list of disorders associated with genes on chromosome 2 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 2.

cancers

Changes in chromosome 2 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, a rearrangement (translocation) of genetic material between chromosomes 2 and 3 has been associated with cancers of a certain type of blood cell originating in the bone marrow (myeloid malignancies).

Trisomy 2, in which cells have three copies of chromosome 2 instead of the usual two copies, has been found in myelodysplastic syndrome. This disease affects the blood and bone marrow. People with myelodysplastic syndrome have a low number of red blood cells (anemia) and an increased risk of developing a form of blood cancer known as acute myeloid leukemia.

2q37 deletion syndrome

2q37 deletion syndrome is caused by a deletion of genetic material from a specific region in the long (q) arm of chromosome 2. The deletion occurs near the end of the chromosome at a location designated 2q37. The size of the deletion varies among affected individuals. The signs and symptoms of this disorder, which may include intellectual disability, autism, short stature, obesity, and characteristic facial features, are probably related to the loss of multiple genes in this region.

other chromosomal conditions

Another chromosome 2 abnormality is known as a ring chromosome 2. A ring chromosome is formed when breaks occur at both ends of the chromosome and the broken ends join together to form a circular structure. Individuals with this chromosome abnormality often have developmental delay, small head size (microcephaly), slow growth before and after birth, heart defects, and distinctive facial features. The severity of symptoms typically depends on how many and which types of cells contain the ring chromosome 2.

Other changes involving the number or structure of chromosome 2 include an extra piece of the chromosome in each cell (partial trisomy 2) or a missing segment of the chromosome in each cell (partial monosomy 2). These changes can have a variety of effects on health and development, including intellectual disability, slow growth, characteristic facial features, weak muscle tone (hypotonia), and abnormalities of the fingers and toes.

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 2 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: Trisomy 2
• MedlinePlus - Health information
  Encyclopedia: Chromosome

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

• Gene Reviews - Clinical summary
• Gene Tests - Genetic tests ordered by healthcare professionals (2 links)
• Research Resources - Tools for researchers (6 links)
• PubMed - Recent literature
• 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 myeloid leukemia ; anemia ; autism ; base pair ; bone marrow ; cancer ; cell ; chromosome ; deletion ; developmental delay ; DNA ; gene ; hypotonia ; leukemia ; microcephaly ; monosomy ; muscle tone ; myelodysplastic syndrome ; myeloid ; rearrangement ; red blood cell ; ring chromosomes ; short stature ; sign ; stature ; symptom ; syndrome ; translocation ; trisomy

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

See also Understanding Medical Terminology.