Gene discovery in primary dystonia using whole exome sequencing

描述(由申请人提供)： 摘要原发性扭转肌张力障碍(PTD)是一组以扭转肌肉痉挛为特征的运动障碍，临床上唯一的症状是肌张力障碍，没有证据表明神经元变性或后天原因。共定位了8个PTD基因座(DYT1、2、4、6、7、13、17和21)，但只分离到两个基因(TOR1A-DYT1和THAP1-DYT6)。不同形式的PTD之间明显的位点异质性、外显性降低和显著的表型重叠限制了位置克隆方法在肌张力障碍基因发现中的成功。新的第二代测序技术与整个外显子组捕获文库相结合，彻底改变了我们识别致病突变的能力。外显子组测序的基础是捕获一个人基因组的所有外显子，并对它们进行测序，平均覆盖深度为30倍。我们建议应用外显子测序来发现四个多代肌张力障碍家系的致病突变。我们将确定每个家庭中一组受影响的个体共享的编码变化。这些变化将在其余家庭成员中进一步测试是否与疾病共分离。识别出的基因将通过筛选表型相似的小型PTD家系中的其他突变来确认。最后，为了确定与突变相关的表型谱，每个基因都将在一大批单胎PTD病例中进行检查。这项拟议的研究将导致新的PTD基因和致病突变的鉴定，从而为理解该病的分子病理生理学提供关键，并为设计新的治疗措施奠定基础。 公共卫生相关性： 为了找到原发性肌张力障碍的遗传原因，我们将使用一种创新的、强大的技术来筛选选定的肌张力障碍家族中的所有基因，以确定致病突变。为了评估与这些基因突变相关的临床特征，我们将测试一大批原发性肌张力障碍患者。本研究将揭示原发性肌张力障碍的新致病基因，从而有助于我们对疾病机制的理解，并为开发新的治疗方法提供依据。

DESCRIPTION (provided by applicant): ABSTRACT Primary torsion dystonias (PTD) are a group of movement disorders characterized by twisting muscle contractures, where dystonia is the only clinical sign and there is no evidence of neuronal degeneration or an acquired cause. There are eight PTD loci assigned (DYT1, 2, 4, 6, 7, 13, 17 and 21), but only two of the genes (TOR1A-DYT1 and THAP1-DYT6) have been isolated. Apparent locus heterogeneity, reduced penetrance and significant phenotypic overlap between different forms of PTD limit the success of positional cloning approaches for dystonia gene discovery. New second generation sequencing technologies combined with whole exome capture libraries have revolutionized our ability to identify disease-causing mutations. Exome sequencing is based on capturing all exons of an individual's genome and sequencing them to an average 30X depth of coverage. We propose to apply exome sequencing to discover causative mutations in four multi- generation dystonia families. We will identify coding changes shared by a group of affected individuals in each family. These changes will be further tested for co-segregation with the disease in the remaining family members. The identified genes will be confirmed by screening for additional mutations in a collection of phenotypically similar small PTD families. Finally, in order to define the phenotypic spectrum associated with mutations, each gene will be examined in a large cohort of singleton PTD cases. The proposed research will lead to the identification of novel PTD genes and pathogenic mutations thus providing a key to understanding the molecular pathophysiology of the disease and the foundation for devising new therapeutic interventions. PUBLIC HEALTH RELEVANCE: PROJECT NARRATIVE To find genetic causes of primary dystonia, we will use an innovative, powerful technique to screen all genes in selected dystonia families to identify causative mutations. To assess the clinical features associated with mutations in these genes, we will test a large cohort of primary dystonia patients. This research will reveal new causative genes for primary dystonia, thus contributing to our understanding of disease mechanism and providing a basis for development of new therapies.