Adenine phosphoribosyltransferase deficiency in a female with gout

[Properties of hypoxanthineguanine-phosphoribosyltransferase (HGPRTase) in a gout patient with partial deficiency of this enzyme (author's transl)]

Some physicochemical properties of HGPRTase were studied in hemolysates and fibroblasts of a gout patient with partial deficiency of this enzyme. In comparison to normal HGPRTase the mutant enzyme from erythrocytes was found to have an elevated apparent Km-value for hypoxanthine and guanine and a lower Km-value for PRPP. The patient's enzyme from erythrocytes is more stable at +4 degrees C and +80 degrees C, the enzyme from fibroblasts more labile than that of controls. The inhibition of the mutant enzyme by some purine nucleosides and -nucleotides differed from that found in controls. No evidence was shown for an inhibitor of the patient's HGPRTase from erythrocytes. Ultracentrifugation of hemolysate in a saccharose gradient revealed no difference in the sedimentation coefficient.

Complete deficiency of adenine phosphoribosyltransferase. Report of a family

We studied the clinical and biochemical manifestations of complete adenine phosphoribosyltransferase deficiency in the kindred of a male homozygous child excreting stones of 2,8-dihydroxyade-nine. Abnormal amounts of adenine, 8-hydroxyade-nine and 2,8-dihydroxyadenine (25 per cent of total purine metabolites) appeared in the urine of the propositus and his clinically normal brother, but not in heterozygotes or a control. Adenine phosphoribosyl-transferase activity in erythrocytes was less than 1 per cent of normal in both homozygotes and varied from 20 to 57 per cent of normal in six heterozygotes. Heterozygotes exhibited neither hyperuricemia nor gout. Treatment of the propositus with allopurinol and a low purine diet stopped stone formation. In addition, excretion of 2,8-dihydroxyadenine decreased. An autosomal recessive mode of inheritance with variable expression in the phenotype is indicated. Homozygotes may be detected by their raised urinary adenine levels or absence of detectable erythrocyte adenine phosphoribosyltransferase activity (or both).