Hematopoietic Stem Cell Transplantation in Infantile Osteopetrosis: Lessons from a Resource-Limited Setting.

Infantile Osteopetrosis is a rare inherited bone disorder characterized by a reduced or complete lack of osteoclast function, leading to defective bone resorption and increased bone density. The defective osteoclast differentiation or function is of hemopoietic origin, thus making Hematopoietic stem cell transplantation (HSCT) the only curative treatment option for this condition. This retrospective study analysed the data of 10 cases of osteopetrosis, undergoing fully HLA-matched HSCT, at AFBMTC from April 2016 to December 2025. Among the cohort, 6(60%) were male with a mean age of 16.09 ± 14.39 months at the time of HSCT. Genetic mutation analysis was available in only four cases (3 had TCIRG1, and 1 case had RANK mutation). All patients received myeloablative conditioning with Fludarabine and Busulfan. Bone marrow harvest was the source of stem cells in all cases except one. Cyclosporine-induced hypertension was the most common complication documented in 100% of cases, followed by Neutropenic fever in 9(90%) cases, mucositis in 6(60%) cases, and VOD in 3 cases (30%). Acute GVHD was documented in 3 (30%) cases, while chronic GVHD was documented in 2(20%). Two (20%) cases had post-HSCT hypercalcemia. Mixed Chimerism was observed in 8 cases (80%) in the first 100 days but did not affect transplant outcomes. OS and DFS for the study were 80%. The cause of death was refractory seizures in one patient, while another patient died due to gut GVHD and septicemia. HSCT at an early age in IO can lead to a good quality of life in this potentially fatal disease.