Unrelated hematopoietic stem cell transplantation for Cernunnos-XLF deficiency.

Cernunnos-XLF deficiency is a rare CI characterized by a defective DNA DSB repair mechanism. Its clinical manifestations are growth retardation, dysmorphic features, malformations, and severe B- and T-cell lymphopenia. BM failure may complicate the clinical picture. To date, there have been no described patients with CSy undergoing allogeneic HSCT. We report a case of CSy treated successfully with unrelated allogeneic HSCT after a reduced-intensity conditioning regimen. Two yr after HSCT, the patient maintains full donor engraftment, normal hematopoiesis, and progressively improving immune competence, thus suggesting that HSCT may be the treatment of choice for CSy.