Haematopoietic stem cell transplant for hyper-IgM syndrome due to CD40 defects: a single-centre experience.

Hyper-IgM syndrome due to CD40 deficiency (HIGM3) is a rare disease with only a few reported cases of haematopoietic stem cell transplantation (HSCT). In retrospective study, we reviewed all patients with HIGM3 who underwent HSCT at King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia, between 2008 and 2013. Six patients were identified. Three male and three female patients from three families. The median age of diagnosis was 13 months (range, 1-28 months). All lacked CD40 expression on B cells by flow cytometry. The median time from diagnosis to transplantation was 8.5 months (range, 1-17 months). For all patients, the donors were HLA-identical siblings, with the exception of one patient for whom the donor was a sibling with one antigen mismatch. The conditioning regimen was busulfan and cyclophosphamide in five patients and busulfan, cyclophosphamide and antithymocyte globulin in one patient. For GVHD prophylaxis, cyclosporine and methotrexate was used. All patients engrafted. The survival rate was 100%, with a median follow-up of 54 months (range, 30-116 months). One patient developed acute GVHD. All patients showed complete immune recovery with positive CD40 expression on B cells and discontinued IVIG replacement. Our study shows that HSCT is potentially effective at curing the disease.