Adenosine Deaminase

Adenosine deaminase (ADA) is an enzyme of the purine metabolism which catalyzes the irreversible deamination of adenosine and deoxyadenosine to inosine and deoxyinosine, respectively. This ubiquitous enzyme has been found in a wide variety of microorganisms, plants, and invertebrates. In addition, it is present in all mammalian cells that play a central role in the differentiation and maturation of the lymphoid system. Two distinct adenosine deaminases, ADA1 and ADA2, are found in humans. ADA1 has an important role in lymphocyte function and inherited mutations in ADA1 result in severe combined immunodeficiency. ADA2 belongs to the novel family of adenosine deaminase growth factors (ADGFs), which play an important role in tissue development.

ADA plays a critical role in various diseases. Interestingly, Both genetic ADA deficiency and ADA overexpression may cause diseases. Generally appreciated is the notion that inherited genetic ADA deficiency represents the main cause of severe combined immunodeficiency disease (SCID), accounting for about 15% of all SCID cases. Conversely, overexpression of ADA may be closely related to hemolytic anemia, liver cancer, breast cancer, etc.