l l l PHAGOCYTES, GRANULOCYTES, & MYELOPOIESIS Comment on Stepensky et al, page 5078 SNAREing a new cause of neutropenia

In this issue of Blood, Stepensky et al identify mutations of VPS45 as a new cause of congenital neutropenia and primary myelofibrosis.1 Severe congenital neutropenia (SCN)is characterized by severe isolated neutropenia from birth, recurring bacterial infections, and a marked propensity to develop a myelodysplastic syndrome or acute myeloid leukemia. SCN is a genetically heterogeneous disorder (see figure). Mutations of ELANE encoding neutrophil elastase (NE) account for;60 % of cases (all in autosomal dominant or sporadic SCN). Mutations of HAX1, G6PC3, GFI1, G6PT1, WAS, and CSF3R collectively account for approximately 10 % to 20 % of cases of SCN. Thus, the genetic basis for approximatel