Two paternal mosaicism of mutation in ELANE causing severe congenital neutropenia exhibit normal neutrophil morphology and ROS production

Severe congenital neutropenia caused by ELANE gene mutation is a rare disease. To date, only four families were reported with mosaicism. Here we examined the morphology and function of granulocytes isolated from two patients and their mosaic fathers. Analysis of granulocytes isolated from the fathers revealed no genetic mutations. DNA extracted from fractionated peripheral blood mononuclear cells (PBMCs) and fingernails obtained from both fathers did harbor the mutation, suggesting mosaicism. Granulocytes isolated from the patients displayed significantly weaker ionomycin-induced intracellular reactive oxygen species (ROS) responses than those isolated from the fathers. Both patients showed increased expression of neutrophil elastase, whereas the mosaic fathers showed normal expression. Taken together, the results suggest that granulocytes from these SCN patients are immunocompromised, whereas those from the mosaic fathers are normal. These findings may provide new insight into disease diagnosis, prognosis, therapy and genetic counseling.