Reticular dysgenesis (RD) is a rare inborn error of immune cell formation defined by severe combined immunodeficiency, agranulocytosis and sensorineural deafness. We report a case of successful haploidentical maternal hematopoietic stem cell transplantation (HSCT) in a boy with RD detected by TREC newborn screening. The patient was admitted to our hospital at 2 weeks of age and was kept in laminar-air flow / hepa-filtered isolation until HSCT was performed at 8 weeks of age with a busulfan, fludarabine conditioning regime. Except few episodes of acute skin graft-versus-host disease (aGVHD) the peritransplant period was uneventful. The patient was discharged 7 weeks post-HSCT. At 18 months of age cochlear implants were placed. The patient was thriving well, showed full donor chimerism and a T cell count >
1000 TCRab + CD3 + cells/µl after one year. Our case highlights that severely immune-compromised patients with RD benefit from early diagnosis by newborn screening, immediate isolation to prevent infections, and early haploidentical HSCT to overcome neonatal neutropenia and establish protective immunity.