Over the past decade, we have developed Drosophila as model system to understand SMN function using an allelic series of transgenic flies expressing SMA-causing missense mutations that recapitulates the full range of phenotypic severity seen in human patients (Matera et al., 2019; Gupta et al., 2021; Praveen et al., 2012; Praveen et al., 2014; Garcia et al., 2013; Garcia et al., 2016; Gray et al., 2018; Spring et al., 2019; Raimer et al., 2020; Garcia et al., 2024). The gene discussed is SMN1; the disease is proximal spinal muscular atrophy.