Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY, United States of America.
Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT, United States of America.
PLoS One. 2019 Aug 12;14(8):e0220512. doi: 10.1371/journal.pone.0220512. eCollection 2019.
Essential tremor (ET) is one of the most common movement disorders. The etiology of ET remains largely unexplained. Whole genome sequencing (WGS) is likely to be of value in understanding a large proportion of ET with Mendelian and complex disease inheritance patterns. In ET families with Mendelian inheritance patterns, WGS may lead to gene identification where WES analysis failed to identify the causative single nucleotide variant (SNV) or indel due to incomplete coverage of the entire coding region of the genome, in addition to accurate detection of larger structural variants (SVs) and copy number variants (CNVs). Alternatively, in ET families with complex disease inheritance patterns with gene x gene and gene x environment interactions enrichment of functional rare coding and non-coding variants may explain the heritability of ET. We performed WGS in eight ET families (n = 40 individuals) enrolled in the Family Study of Essential Tremor. The analysis included filtering WGS data based on allele frequency in population databases, rare SNV and indel classification and association testing using the Mixed-Model Kernel Based Adaptive Cluster (MM-KBAC) test. A separate analysis of rare SV and CNVs segregating within ET families was also performed. Prioritization of candidate genes identified within families was performed using phenolyzer. WGS analysis identified candidate genes for ET in 5/8 (62.5%) of the families analyzed. WES analysis in a subset of these families in our previously published study failed to identify candidate genes. In one family, we identified a deleterious and damaging variant (c.1367G>A, p.(Arg456Gln)) in the candidate gene, CACNA1G, which encodes the pore forming subunit of T-type Ca(2+) channels, CaV3.1, and is expressed in various motor pathways and has been previously implicated in neuronal autorhythmicity and ET. Other candidate genes identified include SLIT3 which encodes an axon guidance molecule and in three families, phenolyzer prioritized genes that are associated with hereditary neuropathies (family A, KARS, family B, KIF5A and family F, NTRK1). Functional studies of CACNA1G and SLIT3 suggest a role for these genes in ET disease pathogenesis.
特发性震颤（ET）是最常见的运动障碍之一。ET 的病因在很大程度上仍未得到解释。全基因组测序（WGS）可能有助于了解具有孟德尔和复杂疾病遗传模式的很大一部分 ET。在具有孟德尔遗传模式的 ET 家族中，WGS 可能导致基因识别，而 WES 分析由于基因组整个编码区域的覆盖不完全，无法识别导致单核苷酸变异（SNV）或插入缺失的原因，此外还可以准确检测到较大的结构变异（SV）和拷贝数变异（CNV）。或者，在具有基因 x 基因和基因 x 环境相互作用的复杂疾病遗传模式的 ET 家族中，功能罕见编码和非编码变异的富集可能解释 ET 的遗传性。我们对纳入家族性特发性震颤研究的 8 个 ET 家族（n = 40 人）进行了 WGS。分析包括基于人群数据库中的等位基因频率过滤 WGS 数据、罕见 SNV 和插入缺失分类以及使用混合模型核自适应聚类（MM-KBAC）测试进行关联测试。还对在 ET 家族中分离的罕见 SV 和 CNV 进行了单独分析。使用 phenolyzer 对家族内鉴定的候选基因进行优先级排序。在分析的 8 个家族中有 5 个（62.5%）家族确定了 ET 的候选基因。在我们之前发表的研究中，对这些家族的亚组进行的 WES 分析未能确定候选基因。在一个家族中，我们在候选基因 CACNA1G 中发现了一个有害和破坏性的变异（c.1367G>A，p.（Arg456Gln）），该基因编码 T 型钙（Ca 2+）通道的孔形成亚基，CaV3.1，在各种运动途径中表达，并与神经元自激和 ET 有关。鉴定的其他候选基因包括编码轴突导向分子的 SLIT3，在三个家族中，phenolyzer 优先考虑与遗传性神经病相关的基因（家族 A，KARS，家族 B，KIF5A 和家族 F，NTRK1）。CACNA1G 和 SLIT3 的功能研究表明这些基因在 ET 疾病发病机制中的作用。
