Cross-sectional disease progression (SPRS score/disease duration) was between 0.83 and 1.7 points per year in a large case series of 278 patients with SPG4 (Rossi et al., 2022), ranging from 1.08 points per year for SPG4 to 1.37 points per year for SPG11 in a large series of childhood-onset HSP (Giordani et al., 2021), and was 0.56 points per year in 34 cases from 28 families with SPG5 (Schöls et al., 2017). This evidence concerns the gene SPAST and hereditary spastic paraplegia.