Activities of Hypoxanthine-Guanine Phosphoribosyltransferase and Adenine Phosphoribosyltransferase in Erythrocytes from Patients with Down's Syndrome

It has been reported that the serum level of uric acid is elevated in Down's syndrome. The present study was undertaken to investigate whether the regulation mechanism of uric acid biosynthesis by hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and adenine phosphoribosyltransferase (APRT) is impaired in Down's syndrome. The activities of HGPRT and APRT in erythrocytes were determined in 14 cases of Down's syndrome and 10 cases of healthy children. There was no significant difference in activities of both enzymes between Down's syndrome and controls. These findings indicate that the activity of HGPRT or APRT may not be controlled by chromosome 21.