Abstract: Objective To investigate the efficacy of hematopoietic stem cell transplantation (HSCT) with low intensity conditional regimen in the treatment of Fanconi anemia (FA), and to provide basis for the optimization of FA transplantation. Methods The clinical data and follow-up results of patients with FA treated by HSCT in our hospital from January 2018 to January 2021 were retrospectively analyzed. Results There were 3 children ( 1 girl and 2 boys) with FA. The median age of onset was 6 . 1 ( 3 . 6 - 13 . 4 ) years, and the median age of transplantation was 7 .2 ( 5 . 7 - 14. 0) years. The 3 patients were treated with HSCT from HLA-mismatched unrelated donor ( 9 /10 ), HLA-matched sibling donor ( 10 /10 ) and HLA-matched unrelated donor ( 10 / 10 ), respectively. The conditional regimen consisted of busulfan, low dose of cyclophosphamide ( 40 mg/kg) and antithymocyte globulin. In the 3 children with FA, the median number of returned mononuclear cells was 9 . 0 ( 8 . 9 - 11 . 2 ) ×108 /kg, and the median number of peripheral CD 34 + cells was 4 . 5 ( 3 . 1 - 5 . 2 ) ×106 /kg. Hematopoietic function was reconstructed in all the 3 children with FA. The median time of neutrophils engraftment was 12 ( 12 - 14 ) days, and the median time of platelet engraftment was 13 ( 12 - 14 ) days. Follow-up was performed to April 2021 . Two patients survived without events, and 1 patient died due to the complications of severe infection and graft-versus-host disease (GVHD) grade Ⅲ. Conclusion HSCT with low intensity of conditional regimen is feasible for the treatment of FA, and it is necessary to continuously explore individualized HSCT regimens for FA.

Key words: Fanconi anemia; hematopoietic stem cell transplantation; graft versus host disease; low intensity conditional regimen