[The genetic basis of post-bone marrow transplant thrombotic microangiopathy: is this the last piece of the puzzle?].

Transplant-associated thrombotic microangiopathy (TA-TMA) is a complication of hematopoietic stem cell transplantation (HSCT) associated with kidney injury and significant mortality. Recent studies indicate that dysregulation of the alternate complement pathway may be at the basis of the development of TA-TMA. Currently, there are no pre-transplant screening tools to identify patients at risk. To explore the mechanism of TA-TMA, we performed a genetic study that allowed us to identify the deletion of the CFHR3-CFHR1 region in homozygosity. We report the clinical case of a 47-year-old woman who underwent haploidentical HSCT complicated by TA-TMA confirmed by renal biopsy. The patient discontinued treatment with calcineurin inhibitors (potential inducers of TA-TMA) with a brief introduction of prednisone until complete resolution of renal damage and microangiopathy. Identifying genetic variants that affect the mechanism of the alternate complement pathway could help in the stratification of the risk of TA-TMA and in implementing a personalized therapeutic approach.