Diagnostic and Therapeutic Challenges in Lesch–Nyhan Syndrome: A Case Report of a Sri Lankan Child Presenting with Self-Mutilation and Hyperuricaemia

Abstract

Lesch–Nyhan syndrome (LNS) is a rare X-linked recessive disorder caused by hypoxanthine-guanine phosphoribosyl transferase deficiency, resulting in hyperuricaemia, neurological dysfunction, and self-mutilation. We report a 3-year-10-month-old Sri Lankan boy who initially presented in infancy with irritability, excessive crying, and sleep disturbance, which were overlooked. He later developed developmental delay, dystonia, and self-injurious behaviour. Investigations revealed hyperuricaemia, hyperuricosuria, cerebral atrophy, absent red cell HPRT enzyme activity, and a pathogenic HPRT1 variant (c.402+1G>A). Treatment included allopurinol and dietary modification, but xanthine stones developed due to overtreatment. Early uric acid testing for prompt LNS diagnosis and allopurinol monitoring to prevent xanthine nephrolithiasis are essential.