An autosomal recessive deficiency of the purine salvage enzyme adenosine deaminase which results in severe combined immunodeficiency disease (scid). the most common form of scid, accounting for about 50% of autosomal recessive cases. the first disease for which gene therapy was applied.

Adenosine deaminase deficiency (ADA deficiency) is a metabolic disorder that causes immunodeficiency. It is caused by mutations in the ADA gene...