Abstract
OBJECTIVE: Childhood cyclic neutropenia (CN) is a rare hematopoietic disorder. We describe the clinical phenotype, diagnostic features, and management of a pediatric CN case caused by a de novo ELANE mutation, to improve clinical recognition and care. METHODS: We retrospectively analyzed clinical, laboratory, and genetic data from a 7-year-old girl with CN, combined with bioinformatics and literature review to explore genotype-phenotype correlations and optimal therapy. RESULTS: The patient presented with classic 21-day cyclic episodes of fever, oral ulcers, and lymphadenopathy. Peripheral blood absolute neutrophil count (ANC) fell to 0.04×10(9)/L at nadir, accompanied by monocytosis. Whole-exome sequencing identified a de novo heterozygous ELANE c.416C>T (p.Pro139Leu) variant. The Pro139 residue is highly conserved across species, and substitution is predicted to impair neutrophil elastase structure and function. The patient responded well to recombinant human granulocyte colony-stimulating factor (rhG-CSF) plus infection control and supportive care and is currently awaiting hematopoietic stem cell transplantation (HSCT). CONCLUSION: Pediatric CN features periodic fever and mucosal infection. Diagnosis requires both cyclic neutropenia documented by serial monitoring and pathogenic ELANE variant confirmation. rhG-CSF remains first-line therapy. Identification of this de novo c.416C>T variant broadens the genotypic spectrum of ELANE-related CN. Early and accurate diagnosis, individualized treatment, and long-term follow-up are critical to improve outcomes.