Urate metabolism in heterozygotes for HGPRTase deficiency.

Abstract

One of the unsolved problems with regard to HGPRTase deficiency has been the occult nature of the abnormality in the heterozygote. Many heterozygotes have shown erythrocyte HGPRTase activity within the normal range (1), although our studies have suggested that this finding is chiefly found in heterozygotes for the severe HGPRTase deficiency which is manifested as the LeschNyhan syndrome. In the less severe HGPRTase deficiency (which is manifested as urate overproduction with minimal neurological signs) our findings have shown a wide range of HGPRTase activities in heterozygotes from as low as 22% of normal up to completely normal values (2). Likewise, the serum urate concentrations in these heterozygotes have most often been found to be normal (1). Some years ago, however, we demonstrated abnormalities of urate metabolism in three heterozygotes with normal serum urate concentrations (3) and we have now extended these studies to a total of nine heterozygotes, all of whom, in one way or another, have demonstrated some abnormality of urate metabolism.