CAPN1 and hereditary spastic paraplegia: Loss-of-function mutations in CAPN1 are known to cause cerebellar ataxia (Wang et al., 2016) and hereditary spastic paraplegia (HSP) (Gan-Or et al., 2016) with the number of ataxia and/or pure HSP patients reporting CAPN1 mutations rapidly increasing (Mereaux et al., 2021).