Department of Brain Disease Research, Matsumoto, Japan.
Department of Medicine (Neurology and Rheumatology), Shinshu University School of Medicine, Matsumoto, Japan.
J Hum Genet. 2017 Oct;62(10):923-925. doi: 10.1038/jhg.2017.63. Epub 2017 Jun 22.
The causative mutation for spinocerebellar ataxia type 31 (SCA31) is an intronic insertion containing pathogenic pentanucleotide repeats, (TGGAA). We examined to what degree the inserted repeats were unstable during transmission. In 14 parent-child pairs, the average change of onset age was -6.4±7.3 years (mean±s.d.) in the child generation when compared with the parent generation. Of the 11 pairs analyzed, six showed expansion of inserted repeat length during transmission, and five showed contraction. On average, the inserted repeats expanded by 12.2±32.7 bp during transmission, but their mean length (with a 95% confidence interval) was not significantly different between parent and child generations. We consider that the length of the inserted repeats in SCA31 is changeable during transmission, but inter-generational instability is not marked, as far as the current sizing method can determine.
导致脊髓小脑共济失调 31 型（SCA31）的致病突变是一个含有致病性五核苷酸重复（TGGAA）的内含子插入。我们研究了在传递过程中插入的重复序列不稳定的程度。在 14 对亲子对中，与亲代相比，子代的发病年龄平均变化为-6.4±7.3 岁（平均值±标准差）。在分析的 11 对中，有 6 对在传递过程中显示插入重复长度的扩展，有 5 对显示收缩。平均而言，插入的重复序列在传递过程中扩展了 12.2±32.7bp，但它们的平均长度（95%置信区间）在亲代和子代之间没有显著差异。我们认为，就目前的测序方法而言，SCA31 中插入重复序列的长度在传递过程中是可变的，但代际不稳定性并不明显。
