Another family was found within a large genetic study carrying a homozygous NFASC variant associated spinal muscular atrophy (Smigiel et al., 2018) and a homozygous missense mutation leads to significant loss of NFASC protein in induced pluripotent stem cell-derived neurons from affected subjects (Monfrini et al., 2019). Here, NFASC is linked to proximal spinal muscular atrophy.