Severe Congenital Neutropenia With Negative Whole-Exome Sequencing Managed With Hematopoietic Stem Cell...

Kostmann syndrome, also known as severe congenital neutropenia, is a congenital disorder characterized by genetic mutations that prevent the progression of myeloid differentiation in the bone marrow. Most cases are associated with specific genetic mutations, including those in HAX1 and ELANE. Treatment with antibiotics and granulocyte colony-stimulating factor (G-CSF) is primarily prophylactic. We report a pediatric case of severe congenital neutropenia present since birth, with negative whole-exome sequencing (WES), complicated by multiple hospital admissions for recurrent infections and subsequent progression to myelodysplastic syndrome with excess blasts associated with monosomy 7, for which the patient ultimately underwent hematopoietic stem cell transplantation (HSCT). This case highlights that many patients with Kostmann syndrome can present with negative genetic testing and draws attention to the importance of surveillance for malignant transformation.