Bell et al. also reported a case series of five patients with heterozygous SPG7 pathogenic variants (three with p.Ala510Val, one with p.Gln447Ter, and one with p.Ala759Thr), all with isolated optic atrophy but without any of the classical symptoms seen with HSP [26]. The gene discussed is SPG7; the disease is hereditary spastic paraplegia.