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.