Successful non-myeloablative allogenic bone marrow transplantation in a child with severe congenital neutropenia complicated by chronic pulmonary infection.

We herein describe a 2-year-old boy with severe congenital neutropenia (SCN) who was successfully treated with reduced-intensity bone marrow transplantation (HSCT). He had suffered recurrent episodes of bacterial pneumonia from 12 months of age, and was found to have severe neutropenia with white blood cell counts below 100/μl. The patient harbored a heterozygous missense mutation in ELANE exon 4 (p.Gln134Pro, NM_001972.2: c.401A>C). This was a novel mutation. Due to intractable pneumonia and severe persistent neutropenia, reduced-intensity HSCT was performed from an HLA-matched sibling donor. The preparative regimen consisted of melphalan, fludarabine, and 4 Gy of total body irradiation. Hematopoietic engraftment was rapidly obtained, i.e., by day +14, and complete donor chimerism was subsequently achieved. The lung complications observed pre-transplantation markedly improved after neutrophil recovery, i.e., by day +60. We concluded that HSCT is a useful treatment for SCN patients, especially for those at high risk of leukemic transformation. Fludarabine-based reduced-intensity HSCT may represent a safe and effective therapeutic option for patients with SCN who need HSCT even if they have intractable infectious complications.