A patient with purine nucleoside phosphorylase deficiency: enzymological and metabolic aspects

1. Enzymological and metabolic data in a patient with nucleoside phosphorylase (NP) deficiency are described. 2. Incubation of intact NP-deficient red cells with [14C]adenosine showed a rapid uptake and conversion to inosine. Almost no radioactivity was incorporated in the adenosine nucleotides and no hypoxanthine labeling could be detected. 3. Incubation with [14C]inosine resulted in a rapid conversion to IMP in the normal intact red cells but in an accumulation of inosine in the medium with the erythrocytes of the patient, proving again that a NP deficiency is present. 4. The high PRPP level found may result from impaired consumption due to lack of substrates for the salvage enzyme HGPRT. 5. Incubation with [14C]hypoxanthine and [14C]adenine showed that normal HGPRT and APRT activities were present in the NP-deficient red cells. 6. In serum and urine of the patient the levels of inosine and guanosine were considerably increased, while the serum and urinary levels of uric acid were very low. In the two deceased sisters NP deficiency was also strongly suggested by analyses of the serum purines, of stored deep frozen samples.