HLH: watch and wait, or act and cure?

If hemophagocytic lymphohisticytosis (HLH)–causing mutations are found in a well child, should that patient receive a bone marrow transplant? In this issue of Blood , Lucchini et al have collected a unique subset of patients with biallelic mutations causing HLH and provide an important recommendation for the management of asymptomatic carriers (ACs) with the same mutation as affected siblings, index cases (ICs). 1