CAPN1 and hereditary spastic paraplegia: SA associated pathogenic variants have been identified in genes originally associated with hereditary cerebellar ataxia (HCA) or hereditary spastic paraplegia (HSP) forms, including the SPG7, SACS, FXN, ATXN1, CYP27A1, CAPN1, SETX, SYNE1, CACNA1A, AFG3L2, GBA2 and other genes [1, 3–5].