Spinocerebellar ataxia type 6: CAG repeat expansion in α1a voltage-dependent calcium channel gene and clinical variations in japanese population
✍ Scribed by Takeshi Ikeuchi; Hiroki Takano; Reiji Koide; Shuichi Igarashi; Hajime Tanaka; Dr. Shoji Tsuji; Hitoshi Takahashi; Yoh Horikawa; Yoshiaki Honma; Yoji Onishi; Naoki Nakao; Ko Sahashi; Hiroshi Tsukagoshi; Kiyoharu Inoue
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 604 KB
- Volume
- 42
- Category
- Article
- ISSN
- 0364-5134
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✦ Synopsis
Autosomal dominant spinocerebellar ataxias (SCAs) are clinically and genetically a heterogeneous group of neurodegenerative disorders. Recently, mild CAG repeat expansion in the qA voltage-dependent calcium channel gene has been found to be associated with a type of autosomal dominant SCA (SCA6). We analyzed 98 Japanese families with autosomal dominant SCAs, for whom CAG repeat expansions of the SCA1, S W , Machado-Joseph disease/SCA3, and dentatorubral-pallidoluysian atrophy genes were excluded, and 5 apparently sporadic cases of cortical cerebellar atrophy. The diagnosis of SCA6 was confirmed in 30 families (31%) comprising 47 affected individuals and 1 sporadic case. The size of expanded CAG repeats ranged from 21 to 26 repeat units and was found to be correlated inversely with age at onset. We identified 2 SCAG patients homozygous for expanded CAG repeats, whose ages at onset were earlier than the 95% lower confidence level, suggesting the presence of a gene dosage effect of expanded CAG repeat. Ataxia is the most common initial symptom found in 45 of the 48 patients. Patients with a prolonged disease course showed other accompanying clinical features including dystonic postures, involuntary movements, and abnormalities in tendon reflexes.