Adenosine deaminase deficiency is seen in the following
|A||Common variable immunodeficiency|
|B||Severe combined immunodeficiency|
|C||Chronic granulomatous disease|
In severe combined immunodeficiency there is severe functional impairment of both cell mediated and humoral immunity. It is inherited either as an X linked or autosomal recessive defect. 50% of patients with autosomal recessive SCID are deficient in the enzyme involved in purine metabolism, adenosine deaminase (ADA).