SMA has been modeled in mice (Hsieh-Li et al., 2000), Drosophila (Spring et al., 2019), zebrafish (McWhorter et al., 2003) and C. elegans (Briese et al., 2009) by deleting the endogenous Smn gene and overexpressing the human SMN2 gene. The gene discussed is SMN1; the disease is proximal spinal muscular atrophy.