Onasemnogene Abeparvovec (AVXS-101) for the Treatment of Spinal Muscular Atrophy.

Spinal muscular atrophy (SMA) is a debilitating disorder characterized by degeneration of large motor neurons. It is a heterogeneous group of disorders caused by a homozygous deletion in the survival motor neuron () gene on chromosome 5, resulting in a SMN protein deficiency. Small amounts of SMN protein are also produced by the gene, which that differs from by a single nucleotide.