The FDA on Friday approved the first gene therapy for children aged 2 years or younger with spinal muscular atrophy, a leading genetic cause of infant mortality, according to an agency press release.

Zolgensma (onasemnogene abeparvovec-xioi, AveXis Inc.) is an adeno-associated virus vector-based gene therapy that targets the cause of spinal muscular atrophy (SMA). The vector delivers a fully functional copy of human SMN gene into the target motor neuron cells, according to the FDA. A one-time IV administration of the gene therapy results in expression of the SMN protein in a child’s motor neurons, which improves muscle movement and function, and survival of a child with SMA. Dosing is determined based on the weight of the patient.