SPG26, a complicated form of HSP, is caused by biallelic B4GALNT1 variants and the clinical phenotypes are similar to those observed in B4galnt1 KO mice (Takamiya et al., 1996; Sheikh et al., 1999; Boukhris et al., 2013; Harlalka et al., 2013). The gene discussed is B4GALNT1; the disease is hereditary spastic paraplegia.