Allogeneic stem cell transplantation for patients with congenital amegakaryocytic thrombocytopenia (CAT).

Five patients with confirmed congenital amegakaryocytic thrombocytopenia (CAT) underwent stem cell transplantation (SCT) from HLA-matched related donors at King Faisal Specialist Hospital and Research Center (KFSHRC). The median age at SCT was 3.2 years (range, 0.4-5 years). Conditioning regimen consisted of busulfan (BU) 4 mg/kg p.o. for 4 days (total dose of 16 mg/kg), and cyclophosphamide (CY) 50 mg/kg once daily i.v. for 4 days (total dose of 200 mg/kg). Antithymocyte globulin (ATG) was given i.v. at a dose of 30 mg/kg for 4 days pre-SCT (total of 120 mg/kg); graft-versus-host disease (GVHD) prophylaxis was with cyclosporine and methotrexate. Four patients engrafted and are alive and transfusion independent with a median follow up time of 30 months (range, 16-45 months). One patient failed to engraft and underwent a second SCT 4 months later but died of respiratory failure. We conclude that the use of allogeneic SCT may be curative for such patients.