Umbilical Cord Blood Transplantation in Lesch-Nyhan Syndrome: A Case Report and Literature Review.

Lesch-Nyhan syndrome (LNS) is a rare X-linked disorder caused by hypoxanthine phosphoribosyltransferase 1 (HPRT1) gene mutations, leading to HPRT1 deficiency, hyperuricemia, and severe neurological dysfunction, including self-injurious behavior. Hematopoietic stem cell transplantation (HSCT) has been applied to some inborn errors of metabolism (IEM), yet only a few cases with limited success in LNS have been reported. This case was diagnosed with LNS at nine months of age due to developmental delays. He subsequently received 5/6 human leukocyte antigen-matched umbilical cord blood transplantation (UCBT) at 14 months of age. Myeloablative conditioning included fludarabine, busulfan, and antithymocyte globulin. This patient achieved complete donor chimerism on day 32 after UCBT. Before UCBT, the patient's HPRT1 protein was lower than his parents, but the levels increased after UCBT. At 36 months of age, no self-mutilation was noted, and neurological improvement was found. HSCT is more effective in preventing disease progression in IEM than in reversing established manifestations, making early diagnosis critical. In this case, LNS was diagnosed early, allowing prompt HSCT. To our knowledge, this is the youngest LNS patient to receive HSCT. We propose that early HSCT may contribute to neurological improvements. Early UCBT is feasible and may prevent self-mutilation and promote neurological recovery in LNS. Further studies are needed.