Institut für Humangenetik, Justus-Liebig Universität Giessen, Giessen, Germany.
J Neurol Neurosurg Psychiatry. 2010 Dec;81(12):1396-9. doi: 10.1136/jnnp.2009.180711. Epub 2010 Jun 28.
Spinocerebellar ataxia type 17 (SCA17) is caused by abnormal expansions of CAG/CAA trinucleotides within the TATA-box binding protein gene (TBP). The currently accepted critical threshold of abnormal expansions is ≥43.
To investigate the minimal CAG/CAA expansion within the TBP in SCA17.
285 patients with autosomal-dominant ataxia were examined, and abnormal or borderline expansions of CAG/CAA within TBP in eight cases were found. Of those, four patients from three families had exactly 42 CAG/CAA trinucleotides, that is, one codon less than the currently accepted critical threshold of 43. The four patients presented with a relatively benign phenotype. All had dysdiadochokinesia and dysarthria. Mild gait ataxia was observed in three of the four patients.
The reference definition of at least 43 CAG/CAA codons for pathological SCA17 alleles should be lowered to 42.
脊髓小脑性共济失调 17 型（SCA17）是由 TATA 结合蛋白基因（TBP）内 CAG/CAA 三核苷酸异常扩展引起的。目前公认的异常扩展临界值为≥43。
研究 SCA17 中 TBP 内最小的 CAG/CAA 扩展。
对 285 例常染色体显性共济失调患者进行了检查，发现 8 例 TBP 内 CAG/CAA 异常或临界扩展。其中，来自三个家族的 4 名患者具有完全的 42 个 CAG/CAA 三核苷酸，即比目前公认的 43 个临界值少一个密码子。这 4 名患者表现出相对良性的表型。所有患者均有运动失调和构音障碍。其中 3 名患者有轻度步态共济失调。
病理 SCA17 等位基因中至少 43 个 CAG/CAA 密码子的参考定义应降低至 42。
