ABSTRACT
The severe combined immunodeficiency may be clinically indistinguishable from adenosine deaminase deficiency; lymphopenia, thymic deficiency and infections; hypouricemia; and deficient activity of purine nucleoside phosphorylase (PNP). The abnormality in purine metabolism in purine nucleoside phosphorylase deficiency resembles that of adenosine deaminase deficiency in that each leads to the accumulation of nucleosides and deoxynucleosides. Deficiency of PNP is unique among immunodeficiencies in that patients have impressive hypouricemia and a very low level of excretion of uric acid in the urine. In PNP, deficiency transfusion therapy has variously been reported to produce partial improvement or no improvement in immune function. In an extensive experience with 100 weeks of erythrocyte transfusion therapy in a boy with PNP deficiency, there was a correction of the elevated level of deoxyguanine triphosphate in erythrocytes and leukocytes, as well as a substantial increase in serum concentrations of urate and decrease in urinary nucleoside content.
