Neuromuscular Diseases Research Unit, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA.
Neuron. 2011 Oct 20;72(2):257-68. doi: 10.1016/j.neuron.2011.09.010. Epub 2011 Sep 21.
The chromosome 9p21 amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD) locus contains one of the last major unidentified autosomal-dominant genes underlying these common neurodegenerative diseases. We have previously shown that a founder haplotype, covering the MOBKL2b, IFNK, and C9ORF72 genes, is present in the majority of cases linked to this region. Here we show that there is a large hexanucleotide (GGGGCC) repeat expansion in the first intron of C9ORF72 on the affected haplotype. This repeat expansion segregates perfectly with disease in the Finnish population, underlying 46.0% of familial ALS and 21.1% of sporadic ALS in that population. Taken together with the D90A SOD1 mutation, 87% of familial ALS in Finland is now explained by a simple monogenic cause. The repeat expansion is also present in one-third of familial ALS cases of outbred European descent, making it the most common genetic cause of these fatal neurodegenerative diseases identified to date.
9p21 染色体肌萎缩性侧索硬化症-额颞叶痴呆(ALS-FTD)位点包含最后一个主要的未识别的常染色体显性基因之一,这些基因是这些常见神经退行性疾病的基础。我们之前已经表明,在与该区域相关的大多数病例中,存在一个覆盖 MOBKL2b、IFNK 和 C9ORF72 基因的创始人单倍型。在这里,我们表明 C9ORF72 基因的第一个内含子中存在一个大的六核苷酸(GGGGCC)重复扩展。这种重复扩展在芬兰人群中与疾病完全分离,在该人群中,46.0%的家族性 ALS 和 21.1%的散发性 ALS 都是由这种重复扩展引起的。与 D90A SOD1 突变一起,芬兰的 87%家族性 ALS 现在可以通过简单的单基因原因来解释。重复扩展也存在于三分之一的欧洲血统的散发性 ALS 病例中,使其成为迄今为止发现的这些致命神经退行性疾病的最常见遗传原因。