New Perspectives in the Diagnosis and Treatment of Adenosine Deaminase (ADA) Deficiency

Abstract

Severe combined immunodeficiency (SCID) due to adenosine deaminase deficiency (ADA) exhibits autosomal recessive inheritance, and may account for up to 20% of cases (1). Accumulation of intracellular toxic deoxynucleotides and/or S-adenosyl homocysteine particularly in T cells, is considered responsible for the severe lymphoid depletion and dysfunction observed in affected children (2). Unlike other forms of SCID, this variety is amenable to enzyme replacement therapy using regular fresh irradiated red blood cell transfusions as the source of enzyme. Another form of therapy suggested from in vitro studies, is the use of deoxycytidine which theoretically would act as a competitive substrate for deoxycytidine kinase, the enzyme considered responsible for the intracellular accumulation of deoxy-ATP (dATP). This study reports our experience of various treatments in three ADA deficient children.