Erythrocyte adenosine deaminase, purine nucleoside phosphorylase and phosphoribosyltransferase activity in patients with Down's syndrome

Abstract

The erythrocyte adenosine deaminase, nucleoside phosphorylase, hypoxanthine-guanine phosphoribosyltransferase and adenine phosphoribosyltransferase activities and plasma urate concentrations were measured in 20 cases of Down's syndrome and in 20 age- and sex-matched control subjects. The mean erythrocyte adenosine deaminase and adenine phosphoribosyltransferase activities and plasma urate concentrations were significantly higher in Down's syndrome subjects than in controls ( p < 0.001, p < 0.01 and p < 0.001, respectively). In all subjects studied there was a positive correlation between the erythrocyte adenosine deaminase activity and plasma urate concentration ( r = 0.488, p < 0.005). The concentrations of the erythrocyte adenine nucleotides, AMP, ADP and ATP, did not differ in Down's syndrome ( n = 10) from those of control subjects ( n = 10). The results suggest that the increase of plasma urate concentrations is a consequence of the increase in adenosine deaminase activity in Down's syndrome patients.