[Adenosine deaminase in severe combined immunodeficiency syndrome]

Adenosine deaminase is an enzyme of the purine metabolism whose function is to convert adenosine to inosine and deoxyadenosine to deoxyinosine. The ecto-ADA1 binding to the cell surface through CD26 contributes to the regulation of cytokines and stimulates the proliferation of T cells by activating CD45. The deficiency of this enzyme generates the severe combined immunodeficiency syndrome, characterized by the accumulation of deoxyadenosine and adenine metabolites, which have toxic effects on lymphocytes, affecting DNA synthesis and consequently, clonal expansion. Early diagnosis of this immunodeficiency is essential, as it significantly reduces morbidity and mortality associated with recurrent infections. Recent advances in molecular biology and genetics have led to the identification of genetic defects of many primary immunodeficiencies and the development of promising diagnostic tools and treatment.