Cyclic neutropenia with heterozygous mutation of ELANE in a patient who showed maturation arrest at first presentation

Abstract

Cyclic neutropenia (CyN) and severe congenital neutropenia (SCN) are disorders of neutrophil production leading to recurrent bacterial infections. Mutations of ELANE, which encodes neutrophil elastase, have been mostly associated with CyN and SCN. We report the case of a 21-month-old girl who showed severe neutropenia and maturation arrest of myeloid lineage at the promyelocyte/myeloid stage in the bone marrow at her first presentation. Heterozygous in-frame deletion (IVS4+1G>A) of ELANE was identified by genetic analysis, and she was tentatively diagnosed as having SCN. However, her neutrophil count gradually increased, and her bone marrow reexamination did not show maturation arrest 4 months after the initial visit. Finally, we concluded that regular fluctuations of neutrophil count and bone marrow findings are consistent with CyN. The frequency of recurrent bacterial infections decreased as neutrophil count gradually increased. Confirming the fluctuation of neutrophil count and bone marrow reexamination are significant for discriminating between CyN and SCN.