A Japanese hereditary spastic paraplegia family with a rare nonsynonymous variant in the SPAST gene

Spastic paraplegia (SPG) type 4 is an autosomal dominant SPG caused by functional variants in the SPAST gene. We examined a Japanese family with three autosomal dominant SPG patients. These patients presented with typical symptoms of SPG, such as spasticity of the lower limbs. We identified a rare nonsynonymous variant, NM_014946.4:c.1252G>A [p.Glu418Lys], in all three family members. This variant has previously been reported in a Russian SPG family as a “likely pathogenic” variant.⁵ Ascertainment of additional patients carrying this variant in an unrelated Japanese SPG family further supports its pathogenicity. Molecular diagnosis of SPG4 in this family with hereditary spastic paraplegia is confirmed.