Meta-Biol

• Pathways

Normally in humans, adenosine and deoxyadenosine can be deaminated to inosine and deoxyinosine, catalyzed by ADA (adenosine deaminase). In the absence of ADA activity, however, accumulated nucleosides disrupt lymphoid cell function, leading to severe combined immunodeficiency. Here, we have annotated the failure of normal adenosine and deoxyadenosine deamination due to three missense mutant alleles of ADA, identified in patients with severe combined immunodeficiency and shown to encode unstable or catalytically inactive forms of ADA protein (Hirschhorn et al. 1989, 1990).