Purine Metabolism in Adenosine Deaminase Deficiency

Deoxyadenosine was identified in the urine of a second child with almost undetectable levels of adenosine deaminase (ADA) in erythrocyte lysates. Deoxyadenosine excretion thus appears to be characteristic of ADA deficiency: the acid lability of deoxyadenosine (responsible for the frequent confusion of this abnormal urinary metabolite with adenine) may be used in screening for this defect by isotachophoresis. The deoxynucleotides dATP, dADP and dAMP found initially in the child's erythrocytes (in comparable amounts to ATP, ADP and AMP) disappeared after a successful marrow graft from an unrelated donor, as did the urinary deoxy metabolites. Erythrocyte ADA activity decreased after the marrow graft but was still greater than 10% of normal congruent to 10 weeks after the last red cell transfusion.