Skip Navigation
Genetics Home Reference: your guide to understanding genetic conditions About   Site Map   Contact Us
Home A service of the U.S. National Library of Medicine®
Printer-friendly version


Reviewed July 2013

What is the official name of the ADA gene?

The official name of this gene is “adenosine deaminase.”

ADA is the gene's official symbol. The ADA gene is also known by other names, listed below.

Read more about gene names and symbols on the About page.

What is the normal function of the ADA gene?

The ADA gene provides instructions for producing the enzyme adenosine deaminase. This enzyme is produced in all cells, but the highest levels of adenosine deaminase occur in immune system cells called lymphocytes, which develop in lymphoid tissues. These lymphoid tissues include the thymus, which is a gland located behind the breastbone, and lymph nodes, which are found throughout the body. Lymphocytes form the immune system, which defends the body against potentially harmful invaders, such as viruses or bacteria.

The function of the adenosine deaminase enzyme is to eliminate a molecule called deoxyadenosine, which is generated when DNA is broken down. Adenosine deaminase converts deoxyadenosine, which is toxic to lymphocytes, to another molecule called deoxyinosine, which is not harmful.

How are changes in the ADA gene related to health conditions?

adenosine deaminase deficiency - caused by mutations in the ADA gene

More than 70 mutations in the ADA gene have been identified. Most of these mutations result in the substitution of one protein building block (amino acid) for another amino acid in the adenosine deaminase enzyme. Other mutations cause the enzyme to be unstable or prevent it from being produced at all.

These mutations result in the absence or deficiency of the adenosine deaminase enzyme in cells, preventing the normal breakdown of deoxyadenosine. A buildup of this toxic compound interferes with the development and maintenance of lymphocytes, resulting in severe combined immunodeficiency (SCID), which is characteristic of adenosine deaminase deficiency.

Where is the ADA gene located?

Cytogenetic Location: 20q13.12

Molecular Location on chromosome 20: base pairs 44,619,522 to 44,652,233

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBIThis link leads to a site outside Genetics Home Reference.)

The ADA gene is located on the long (q) arm of chromosome 20 at position 13.12.

The ADA gene is located on the long (q) arm of chromosome 20 at position 13.12.

More precisely, the ADA gene is located from base pair 44,619,522 to base pair 44,652,233 on chromosome 20.

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

Where can I find additional information about ADA?

You and your healthcare professional may find the following resources about ADA helpful.

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

What other names do people use for the ADA gene or gene products?

  • adenosine aminohydrolase

Where can I find general information about genes?

The Handbook provides basic information about genetics in clear language.

These links provide additional genetics resources that may be useful.

What glossary definitions help with understanding ADA?

amino acid ; bacteria ; breakdown ; compound ; deficiency ; DNA ; enzyme ; gene ; immune system ; immunodeficiency ; lymph ; lymphoid ; molecule ; protein ; substitution ; thymus ; toxic

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

See also Understanding Medical Terminology.

References (7 links)


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.

Reviewed: July 2013
Published: February 1, 2016