Abstract • 163

From 1986 to 1998, we performed 24 hematopoietic stem cell transplantations in 21 patients (pts) suffering from the Hurler syndrome, aged of 12 months (m) at time of diagnosis and 25 m at time of transplantation (median). Three patients were transplanted twice. The genetic deficiency was severe in 15 cases (71%, intermediate in 5 and mild in 1 case. Donor ws familial in 12 cases: 8 genotypically identical father and 3 HLA mismatched donors (father in 2 cases, cord blood in 1). Unrelated donors were selected in 12 cases: 2 phenotypically identical and 10 presenting from 1 to 3 mismatches at the allelic level (DPB1* excluded). Conditioning regimen generally consisted of Busulfan 600 mg/m2 plus Endoxan 260 mg/kg and Cyclosporine with Methotrexate for GVHD prophylaxis. 1 patient received T depleted marrow. Anti lymphocyte globulin (ALG) was added for unrelated or familial mismatched transplant: 4 doses pre graft, 20 mg/kg total dose. Nucleated cell doses infused ranged from 1.3 to 9.2× 108 total nucleated cells/kg (median : 4.25). Engraftment was observed in 19/24 patients (79%) (after 2nd transplant in 2 cases). One patient rejected. Graft failure is observed in 5/24 patients (21%) (1 after 2nd transplant). Two patients died (9%) of invasive aspergillosis and IP. Among the 19 alive patients, 3 have disease progression after graft failure and 16 have functional graft (76%) with favorable effects and median follow up of 32 m. Percentage of donor cells is 100% fro 11/16 patients. 8/16 patients (50%) were transplanted from unrelated donors of whom 7 were mismatched pairs. This demonstrates that good results can be obtained using HLA mismatched unrelated donors with addition of ALG and without T cell depletion or irradiation in Hurler syndrome.