Autism genetics: homozygosity mapping and functional validation

描述（由申请人提供）： 自闭症谱系障碍（ASD）影响1%或更多的美国儿童。自闭症谱系障碍的特征是社会行为缺陷，包括语言延迟，异常的社会互动，以及重复或刻板的兴趣或行为。ASD显示出很大的遗传成分，估计遗传率高达60- 90%。然而，ASD的极端异质性是基因发现的一个持续障碍，已知的遗传原因占诊断的不到15%。 尽管高通量测序（HTS）方法允许系统分析整个外显子组甚至整个基因组的遗传变异，但对这些数据的解释面临着尚未解决的分析挑战。使用近亲谱系，其中父母共享祖先，允许识别候选基因，然后可以在非近亲家庭中进行更广泛的分析。血缘家族1]减少ASD的异质性，2]简化HTS分析和验证，和3]提供遗传连锁证据以支持单个家族中特定突变的有效性。初步数据证实，在这样的家系HTS可以有效地识别，在一个公正的方式，隐性遗传因素的ASD相关的近亲和非近亲的患者队列。 这项研究将寻求招募被诊断患有ASD的近亲家庭，进行纯合性定位以定位可能包含导致其ASD的突变的基因组区域，并对受影响的个体进行全基因组测序（WGS）以识别候选变体。此外，将继续分析来自先前研究的近亲家庭的连锁和全外显子组测序数据。本研究将通过以下方式扩展先前的工作：1）生成正常对照的WGS数据以鉴定中东人群中的常见等位基因，从而允许在本研究和许多其他中东WGS研究中进行更快速、更灵敏且最终更便宜的分析; 2]使用酵母模型、转化的体细胞系，产生功能验证通过WGS发现的强候选基因的相对高通量方法，和其他模型系统;和3]使用RNAi产生本研究中发现的候选基因的小鼠模型，以及正在进行的神经元活性依赖性基因研究，以检查去除基因对树突和树突棘形态和突触活性的影响。 最近的研究表明，尽管存在高水平的异质性，但与ASD相关的共同生化途径。这项研究的发现将有助于鉴定构成这些通路的基因，并为治疗ASD提供潜在的药物靶点。

DESCRIPTION (provided by applicant): Autism spectrum disorders (ASDs) affect 1% or more of American children. ASDs are characterized by defects in social behavior, including language delay, abnormal social interactions, and repetitive or stereotyped interests or behaviors. ASDs show a large genetic component, with estimates of heritability as high as 60- 90%. However, the extreme heterogeneity of ASD is a persistent hurdle to gene discovery, and known genetic causes account for less than 15% of diagnoses. Although high throughput sequencing (HTS) methods allow systematic analysis of genetic variation across the entire exome, or even the entire genome, the interpretation of this data faces analytical challenges that have by no means been solved. The use of consanguineous pedigrees, in which parents share ancestry, allows the identification of candidate genes that can then be analyzed more broadly in nonconsanguineous families. Consanguineous families 1] reduce the heterogeneity of ASD, 2] simplify HTS analysis and validation, and 3] provide genetic linkage evidence to support the validity of specific mutations in a single family. Preliminary data confirms that HTS in such pedigrees can efficiently identify, in an unbiased fashion, recessive genetic causes of ASD relevant to both consanguineous and nonconsanguineous cohorts of patients. This study will seek to enroll consanguineous families diagnosed with ASD, perform homozygosity mapping to locate regions of the genome likely to harbor the mutation that causes their ASD, and perform whole genome sequencing (WGS) on the affected individuals to identify candidate variants. Further, linkage and whole exome sequencing data that was generated on consanguineous families from previous studies will continue to be analyzed. This study will expand on the previous work by 1] Generating WGS data on normal controls to identify common alleles within Middle Eastern populations thus allowing swifter, more sensitive and ultimately cheaper analysis in this and many other Middle Eastern WGS studies; 2] Generating relatively high throughput methods of functionally validating strong candidate genes discovered through WGS using yeast models, transformed somatic cell lines, and other model systems; and 3] Using RNAi to generate mouse models of candidate genes discovered in this study, and an ongoing neuronal activity-dependent gene study, to examine the effects of removing the genes on dendrite and dendritic spine morphology and synaptic activity. Recent studies suggest that, despite the high level of heterogeneity, there are common biochemical pathways associated with ASD. The findings from this study will be instrumental in the identification of the genes that make up these pathways, and provide potential pharmaceutical targets for the treatment of ASD.