adenosine deaminase 2
The ADA2 gene provides instructions for making an enzyme called adenosine deaminase 2. This enzyme breaks down molecules called adenosine and 2'-deoxyadenosine. Because this enzyme functions in the spaces between cells, it is described as extracellular. Another form of adenosine deaminase, often called adenosine deaminase 1, breaks down the same molecules inside cells. This other version of the enzyme is produced from the ADA gene.
Researchers are still working to determine what roles the extracellular form of adenosine deaminase plays in the body. Studies suggest that it acts as a growth factor, which means that it stimulates cell growth and division. In particular, the enzyme appears to be involved in the growth and development of certain immune system cells, including macrophages, which are a type of white blood cell that plays a critical role in inflammation. Some macrophages are pro-inflammatory, meaning they promote inflammation, while others are anti-inflammatory, meaning they reduce inflammation. Adenosine deaminase 2 also seems to be essential for keeping the lining of blood vessel walls intact.
At least 15 mutations in the ADA2 gene have been found to cause adenosine deaminase 2 deficiency, a disorder characterized by abnormal inflammation of various organs and tissues, particularly the blood vessels (vasculitis). These mutations severely reduce or eliminate the function of adenosine deaminase 2. Researchers do not fully understand how a loss of this enzyme's function leads to the features of ADA2 deficiency. They speculate that a lack of this enzyme may disrupt the balance between pro-inflammatory and anti-inflammatory macrophages in various tissues, leading to abnormal inflammation. The enzyme's role in maintaining the structural integrity of blood vessels could help explain why the blood vessels are most often affected by inflammation in this disorder.
- adenosine deaminase CECR1
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