Hypoxanthine-Guanine Phosphoribosyltransferase (HGPRT) Deficiency: Effect of Dietary Purines on Enzyme Activity

Abstract

The X-linked, virtually complete deficiency of hypoxanthineguanine phosphoribosyltransferase (HGPRT) activity results in a bizarre neurologic disorder, the Lesch-Nyhan syndrome (Seegmiller, Rosenbloom and Kelley, 1967). In initial reports HGPRT activity was noted as undetectable in erythrocytes from patients with the Lesch-Nyhan syndrome. However, more recently several investigators have noted low but detectable levels of HGPRT activity in erythrocytes from these patients (Mizuno, et al., 1970; Sorenson, 1970). In addition, it is now known that despite this striking reduction in HGPRT activity there is a normal amount of immunologically detectable HGPRT protein present (Rubin, et al., 1971; Arnold, Meade and Kelley 1972). We subsequently found that a given patient would also exhibit a wide variability in HGPRT activity even when assay conditions were standardized. This suggested that envir- onmental factors might be responsible for changes in enzyme actiivty and that one potential approach to therapy of patients with this disease would be activation of the structurally abnormal HGPRT protein. The present report describes the influence of alterations in dietary purine content on the erythrocyte HGPRT activity from three patients with the Lesch-Nyhan syndrome.