HLA factors in transplantation for nonmalignant hematologic disorders.

In this issue of Blood, a study by Horan and colleagues shows that differences in the HLA alleles of patients and unrelated donors in hematopoietic stem cell transplantation (HSCT) for nonmalignant diseases result in increased risk for adverse treatment outcome.(1) This is the largest dataset examined so far for the evaluation of HLA mismatches in HSCT for nonmalignant diseases. It includes predominantly pediatric patients diagnosed with 39 diseases. Many patients received nonmyeloablative conditioning; a significant proportion of the infused grafts were depleted of T-lymphocytes; 6 diseases account for 77% of the cases.