Safety of onasemnogene abeparvovec in an infant with spinal muscular atrophy type 1 and severe neutropenia: A case report and literature review

Spinal muscular atrophy (SMA) is an autosomal recessive, neurodegenerative disorder resulting in severe, progressive hypotonia and muscular weakness. Spinal muscular atrophy is a multisystem disease, however limited information is available regarding its effect on the immune system, bone marrow and the myeloid cell development and function. Currently, three disease-modifying treatments that increase survival motor neuron (SMN) protein expression are available. Among them onasemnogene abeparvovec, an adeno-associated virus-based gene replacement therapy, delivers functional human SMN by a single-dose intravenous infusion and transient transaminasemia is the most significant adverse event. There are no reported cases of patients with SMA and severe hematological abnormalities who received the specific gene therapy. We describe a 10-month-old boy with SMA type 1 and severe neutropenia who was successfully administered onasemnogene abeparvovec, focusing on the investigational and post-treatment challenges as well as his outcome. The treatment was tolerated well, the patient showed neurological improvement and neutropenia resolved confirming the diagnosis of chronic benign neutropenia.