ⓔノート18-6-21　疫学

　欧米のAD–HSPのうち70～80％を純粋型が占めている．SPG4が40～45％と最も頻度が高く，ついでSPG3Aが10％ (SPG3Aは若年発症例に限ると頻度はさらに高くなる)，SPG31が5％，SPG10が3％である1)．AR–HSPのうちSPG11が最も頻度が高く，脳梁の菲薄化と知能障害を合併するAR–HSPの60～80％を占める1)．一見，孤発性にみえても，SPG3AやSPG4などではAD–HSPの不完全浸透やde novo変異のことがある2,3)．

〔瀧山嘉久〕

■文献

  1. Finsterer J, Loscher W, et al: Hereditary spastic paraplegias with autosomal dominant, recessive, X–linked, or maternal trait of inheritance. J Neurol Sci, 2012; 318: 1–18.

  2. Rainier S, Sher C, et al: De novo occurrence of novel SPG3A/Atlastin mutation presenting as cerebral palsy. Arch Neurol, 2006; 63: 445–447.

  3. Depienne C, Tallaksen C, et al: Spastin mutations are frequent in sporadic spastic paraparesis and their spectrum is different from that observed in familial cases. J Med Genet, 2006; 43: 259–265.