Novel ELANE Gene Mutation in a Newborn with Severe Congenital Neutropenia: Case Report and Literature Review

Severe neutropenia is defined as an absolute neutrophil count (ANC) of less than 0.5 × 10 ⁹ /L. Severe congenital neutropenia (SCN) is an inborn disorder with maturation arrest of granulocytes due to various genetic abnormalities, which may lead to immunodeficiency. Among several associated genetic mutations, the variants or heterozygous mutations of the ELANE gene coding neutrophil elastase comprise approximately 50% of the genetic causes of SCN. We present a newborn (male) with severe neutropenia due to a novel ELANE gene mutation. The newborn was born at 38 ^6/7 weeks gestation to a 25-year-old mother with hypertension and morbid obesity. Pregnancy and delivery were uncomplicated but the baby obtained a complete blood count (CBC) on day of life 2 for a work up of hyperbilirubinemia. He was noted to initially have an ANC of 0.2 × 10 ⁹ /L and 0 on subsequent blood counts. A bone marrow biopsy showed a left shift and consistent with myeloid maturation arrest. In direct DNA sequencing analysis, we found an ELANE gene mutation (Val119Glu, V119E), which may be a new gene mutation to cause SCN. The diagnosis of SCN in newborns is usually based on neutropenia identified on a routine CBC. Sufficient awareness and high suspicion of this rare disease can prevent missed or delayed diagnosis of SCN. Our analysis also suggests a new pathological mutation in the ELANE gene and supports the important role of molecular testing in SCN.