SOHO 2026 Annual Meeting

Hematopoietic Stem Cell Transplantation in Infantile Osteopetrosis: Lessons from a resource-limited setting. Background:  Infantile Osteopetrosis is a rare inherited bone disorder characterised 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.  Objective:  To determine the outcome of HSCT in Infantile Osteopetrosis patients in a low and middle-income country. Methods:This retrospective study analysed the data of 10 cases of infantile osteopetrosis at AFBMTC from April 2016 to December 2024. Cases having fully HLA-matched HSCT were included in the study. All patients received myeloablative conditioning with fludarabine and Busulfan. Genetic mutation analysis was available in only three cases (2 had TCIRG1 and 1 case had RANK mutation). Results:Among the cohort, 6(60%) were male with a mean age of 16.09 + 14.39 months at the time of HSCT 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%). Only one case 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.  Conclusion: HSCT is the only curative treatment option that improves the clinical manifestation of infantile osteopetrosis. HSCT at an early age in infantile osteopetrosis can lead to a better quality of life in this potentially fatal disease.