Identification of causal genes for nonsyndromic orofacial clefts using Whole Exome Sequencing

口面裂是世界范围内最常见的先天性畸形之一。在没有任何外科手术的情况下，据报告新生儿死亡率很高。正式的遗传学/流行病学研究表明，OFC的两种最常见的亚型，即非综合征性唇腭裂（nsCL/P）和腭裂（nsCPO），有一个多因素的病因学，其中遗传和环境因素都有助于表型。全基因组关联研究（GWAS）和随后的Meta-analysis）最近在解释nsCL/P的遗传病因学方面取得了重大突破，确定了15个nsCL/P的易感基因座。然而，很大一部分的nsCL/P遗传力仍然有待解释。对于nsCPO来说，GWAS的成功是有限的。事实上，这两种类型的非综合征型OFC往往是散发性的，由于新生儿死亡率高，繁殖率非常低，这表明很大一部分的裂是由个别和罕见的从头突变。GWAS，这主要是针对常见的变异，是不太可能检测到这样的alteration.The的目的，这项研究是确定的致病性从头突变，风险基因，和非综合征OFC的功能途径，使用全外显子组测序（WES）的方法。从我们的非综合征OFC患者的大队列中，我们将选择50个nsCL/P三联体和50个nsCPO三联体（父母分别未受影响）作为发现队列。外显子组捕获将使用Agilent SureSelectv 5 +UTR进行，靶向74 Mb的人类基因组。WES将使用配对末端技术在内部Illumina HiSeq 2500测序平台上运行。将应用用于读段比对、映射和变体识别的严格参数，并且仅当变体不是从任一亲本继承时才保留它们。我们预计，这种方法将产生约150个从头候选变异/基因。为了确定最有希望的候选基因（优先候选基因），将通过不同的统计方法分析和评估检测到的变异，如负荷和途径分析、基因座特异性突变率和有害评分。然后将在Illumina MiSeq系统上对优先候选基因（估计数量：50-60）进行重新测序，在300名nsCL/P个体和300名nsCPO个体的大型独立确认队列中进行。生成的数据将为进一步深入分析提供基础，例如与另一个欧洲小组的WES数据相结合。此外，候选基因将被检查在我们的nsCL/P GWAS荟萃分析data.We预计，这项研究的方法将揭示非综合征性唇腭裂的易感性变异/基因谱，并大大提高我们对颅面发育的理解。

Orofacial clefting (OFC) is one of the most common congenital malformations worldwide. In the absence of any surgical intervention, neonatal mortality is reported to be high. Formal genetic / epidemiological studies have shown that the two most common subtypes of OFC, namely nonsyndromic cleft lip with or without cleft palate (nsCL/P) and cleft palate only (nsCPO), have a multifactorial aetiology in which both genetic and environmental factors contribute to the phenotype. The heritability of nsCL/P has been estimated to be more than 90%.Genome-wide association studies (GWAS) and subsequent meta-analyses have recently led to major breakthroughs in deciphering the genetic aetiology of nsCL/P, with 15 susceptibility loci for nsCL/P being identified. However, a large proportion of the nsCL/P heritability still remains to be explained. For nsCPO, the success of GWAS has been limited. The fact that both types of nonsyndromic OFC are often sporadic and the very low rate of reproduction due to high neonatal mortality suggest that a substantial proportion of clefting is caused by individual and rare de novo mutations. GWAS, which are primarily designed to target common variants, are unlikely to detect such alterations.The aim of this study is the identification of causative de novo mutations, risk genes, and functional pathways for nonsyndromic OFC, using a whole exome sequencing (WES) approach. From our large cohort of nonsyndromic OFC patients we will select 50 triads with nsCL/P and 50 triads with nsCPO (parents unaffected respectively) as a discovery cohort. Exome capture will be performed using Agilent SureSelectv5+UTR, targeting 74 Mb of the human genome. WES will be run on the in-house Illumina HiSeq2500 sequencing platform using paired-end technology. Stringent parameters for read alignment, mapping and variant calling will be applied, and variants will only be retained if they are not inherited from either parent. We anticipate that this approach will yield about 150 de novo candidate variants/genes. In order to identify the most promising candidates for follow-up (priority candidate genes), detected variants will be analysed and evaluated by different statistical approaches, such as burden and pathway analyses, locus-specific mutation rates and detrimental scores. Priority candidate genes (estimated number: 50-60) will then be re-sequenced on the Illumina MiSeq system, in a large independent confirmation cohort of 300 individuals with nsCL/P and 300 with nsCPO. The data generated will provide the basis for further in-depth analyses, such as combining with WES data from another European group. Additionally, candidate genes will be checked for association / sub-phenotype specific effects of common variants in our nsCL/P GWAS meta-analyses data.We anticipate that this study's approach will uncover the spectrum of susceptibility variants/genes for nonsyndromic clefting, and substantially improve our understanding of craniofacial development.