First bone marrow transplantation for mucopolysaccharidosis type I in Vietnam: a case report.

Mucopolysaccharidosis type I (MPS-I) is an inherited lysosomal storage disorder characterized by alpha-L-iduronidase deficiency, leading to progressive multi-organ damage and fatal complications. Early treatment is crucial to improve outcomes, particularly in patients with severe phenotypes. We present the first case of successful allogeneic bone marrow transplantation (BMT) for MPS-I in Vietnam. A 10-month-old girl experienced coarse facial features, congenital dermal melanocytosis spots, kyphoscoliosis developmental delay. Laboratory analyses revealed reduced alpha-L-iduronidase activity and elevated urinary glycosaminoglycans, genetic mutations identified two heterozygous mutations in the IDUA gene, confirmed the diagnosis of MPS-I. At 3 years old, she underwent allogeneic BMT from an HLA-matched sibling donor following conditioning regimen with busulfan, cyclophosphamide, antithymocyte globulin. Neutrophil engraftment was achieved on day +24, and platelet engrafted on day +32. The post-transplant course was complicated by respiratory deterioration requiring 5 days of mechanical ventilation, which was promptly managed and resolved. No graft-versus-host disease occurred. Post-transplant chimerism showed 95.77% donor-derived cells on day +30 and remained stable at 100% from 2 months. The patient demonstrated improvement in clinical symptoms, accompanied by alpha-L-iduronidase activity returned to normal range, urinary glycosaminoglycan levels decreased and remained stable during follow-up. At 12 months, she demonstrated complete immune reconstitution. This case suggests that allogeneic BMT may be a therapeutic approach for patients with MPS-I in resource-limited settings.