[Familial immune deficit and genetic deficiency of adenosine deaminase or of nucleoside phosphorylase (author's transl)].

Two familial enzymopathies, always related to the combined immune deficit, are reviewed. Both are clinically characterized by repeated infections since the birth, leading to fatal issue before age of 4 years. The hereditary deficiency of adenosine deaminase is associated to the deficient functions of T and B lymphocytes. The activity of the enzyme is non detectable in the erythrocytes, strongly reduced in the lymphocytes and in several organs. In hereditary deficiency of nucleoside phosphorylase the functional anomalies of T lymphocytes are observed. The biochemical mechanism of the relation between the two enzymopathies and the deficient function of the immune system is centered on the metabolic pathway of purine nucleosides ans nucleotides.