Hyperuricaemia and choreoathetosis in a child without mental retardation or self‐mutilation — a new HPRT variant

A thirteen‐year‐old boy is described who had uric acid nephrolithiasis, spasticity and choreoathetosis, but no self‐mutilation or mental retardation. Initial studies suggested the presence of the classic Lesch‐Nyhan enzymatic defect; study of the metabolism of [8‐ 14 C]hypoxanthine and [8‐ 14 C]guanine in intact fibroblasts and careful analysis of the data indicated that this was not the case. This child represents a newly identified variant of the HPRT locus.