Takahashi Yuji, Kanai Masahiro, Taminato Tomoya, Watanabe Shoko, Matsumoto Chihiro, Araki Toshiyuki, Okamoto Tomoko, Ogawa Masafumi, Murata Miho
Department of Neurology (Y.T., M.K., T.T., S.W., T.O., M.M.), National Center Hospital, and Department of Peripheral Nervous System Research (C.M., T.A.), National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo; and Department of Neurology (M.O.), Nagahama City Hospital, Japan.
Neurol Genet. 2016 Nov 21;3(1):e123. doi: 10.1212/NXG.0000000000000123. eCollection 2016 Feb.
Spinocerebellar degeneration (SCD) is a group of disorders characterized by progressive ataxia caused by dysfunction and atrophy of the cerebellum or its projections. Approximately one-third of SCD cases are familial SCD, the majority of which are attributed to CAG triplet repeat expansions including spinocerebellar ataxia (SCA)1, SCA2, Machado-Joseph disease (MJD)/SCA3, SCA6, SCA8, SCA12, SCA17, and dentate-rubro-pallido-luysian atrophy (DRPLA). The triplet repeat number of the alleles representing complete penetrance varies among diseases. Generally, there is a gap between the normal alleles and the complete penetrance alleles. Rarely, intermediate alleles with the repeat numbers between the abnormal and normal ranges are observed, although the implications of these intermediate alleles remain ambiguous.
脊髓小脑变性（SCD）是一组以小脑或其投射功能障碍和萎缩导致的进行性共济失调为特征的疾病。约三分之一的SCD病例为家族性SCD，其中大多数归因于CAG三联体重复扩增，包括脊髓小脑共济失调（SCA）1型、SCA2型、马查多-约瑟夫病（MJD）/SCA3型、SCA6型、SCA8型、SCA12型、SCA17型以及齿状红核苍白球路易体萎缩（DRPLA）。代表完全外显的等位基因的三联体重复次数在不同疾病中有所不同。一般来说，正常等位基因和完全外显等位基因之间存在差距。很少观察到重复次数介于异常和正常范围之间的中间等位基因，尽管这些中间等位基因的意义仍不明确。
