Eyal Grunebaum, MD and Chaim M. Roifman, MD
Hemophagocytic lymphohistiocytosis is thought to occur as a primary (familial) form or secondary to infection or malignancy. Recently, several defects in genes important for immune functions were identified in patients with HLH. These include mutations in perforin, the gamma common chain, the receptor for interleukin-2, Slap and purine nucleoside phosphorylase. Since abnormal function of these genes is associated with a wide clinical spectrum, HLH is probably another manifestation of immune deficiency and a thorough immune evaluation should be done in all such patients.