Interestingly, until our study there had not been genetic evidence linking calpain function with SMA development, although recent investigations have described the role of CAPN1 regulating SMN protein (Wang et al., 2019) (de la Fuente et al., 2020), suggesting the use of calpain inhibitors as a therapeutic strategy for SMA treatment (de la Fuente et al., 2019). Here, CAPN1 is linked to proximal spinal muscular atrophy.