Geschwind D H, Perlman S, Figueroa K P, Karrim J, Baloh R W, Pulst S M
Department of Neurology, UCLA School of Medicine, Reed Neurological Research Center, USA.
Neurology. 1997 Nov;49(5):1247-51. doi: 10.1212/wnl.49.5.1247.
Spinocerebellar ataxia type 6 (SCA6) is the most recently identified mutation causing autosomal-dominant cerebellar ataxia without retinal degeneration (ADCA). The SCA6 mutation is allelic with episodic ataxia type 2 (EA-2), but the two differ clinically because of the presence of progressive, rather than episodic, ataxia in SCA6. SCA6 accounts for 12% of families with ADCA in an ethnically heterogeneous population of patients. Clinical examination, quantitative eye movement testing, and imaging data show that the brainstem is normal in most patients with SCA6, especially within the first 10 years of symptoms. Most patients show progressive ataxia from the onset, but several patients show an episodic course resembling EA-2. Thus, SCA6 mutations not only account for patients with ADCA I and ADCA III phenotypes but also for some patients presenting with episodic features that are typical for EA-2. Interestingly, a compound heterozygote for the SCA6 expansion manifested an earlier onset and more rapid course than family members with the same larger expanded allele.
6型脊髓小脑共济失调（SCA6）是最近发现的一种导致常染色体显性遗传性小脑共济失调且无视网膜变性（ADCA）的突变。SCA6突变与2型发作性共济失调（EA - 2）是等位基因，但由于SCA6存在进行性而非发作性共济失调，二者在临床上有所不同。在一个种族异质性患者群体中，SCA6占ADCA家族的12%。临床检查、定量眼动测试和影像学数据显示，大多数SCA6患者的脑干正常，尤其是在症状出现的前10年内。大多数患者从发病起就表现为进行性共济失调，但有几位患者表现出类似EA - 2的发作病程。因此，SCA6突变不仅导致I型和III型ADCA表型的患者出现症状，也导致一些具有EA - 2典型发作特征的患者出现症状。有趣的是，与具有相同较大扩展等位基因的家庭成员相比，SCA6扩展的复合杂合子发病更早，病程进展更快。
