[Investigation of a variant form of hypoxanthine-phosphoribosyl transferase in a family (author's transl)].

In a family study with two patients showing hyperuricaemia, discrete neurological symptoms, as well as gouty arthritis in the older proband, hypoxanthine phosphoribosyl transferase (HPRT) and adenine phosphoribosyl transferase (APRT) were determined in haemolysates and fibroblast extracts. 6 normal subjects and 3 patients with the Lesch-Nyhan syndrome were examined as controls. Reduced HPRT activity by 18% and 12% in the proband and his nephew, respectively, together with an increase to values of 206% and 113% in APRT activity was observed in haemolysates. In fibroblasts the HPRT activity was reduced to 40--43%, but the APRT activity was within the normal range. The studies indicate the presence of a possible variant form of HPRT in these patients.