Identification of causal genes and cellular pathways for idiopathic achalasia on the basis of genome-wide association studies (GWAS)

特发性失弛缓症是一种原发的食道动力障碍。它的特点是食道不动和下食道括约肌(LES)由于肌间神经丛中抑制神经元的丢失而无法放松。虽然这种神经元变性的病理生理学主要尚不清楚，但具有遗传易感性的个体似乎参与了自身免疫过程。在病因水平上，失弛缓症是多因素的，涉及各种风险基因变异和环境因素的累积效应。最近，我们首次使用Illumina免疫芯片对病例对照样本与贲门失弛缓症进行了系统的关联研究，该芯片在基因组区域包含&gt；190 K单核苷酸多态(SNPs)，这些SNPs以前显示与各种自身免疫性疾病相关。这表明，在人类白细胞抗原-DQ受体的细胞质尾部插入8个氨基酸是患失弛缓症的最大风险(Gockel等人。(2014)NAT Genet 46：901-904)。此外，人类白细胞抗原-DQ受体胞外区的两个氨基酸替换独立地增加了幽门失弛缓症的风险。此外，我们还表明，与南欧人相比，北欧人在人类白细胞抗原-DQ受体中插入8个氨基酸的情况较少(Becker等人。(2016)EUR J Hum Genet 24：1228-1231)。这一地理空间南北梯度意味着特发性失弛缓症的患病率可能在不同人群中有所不同。该项目的目的是全面识别特发性贲门失弛缓症的进一步遗传风险变异。为此，将对5000名欧洲患者和6346名种族匹配的对照进行全基因组关联研究。已确定的风险变异将在电子功能研究中进行后续研究，以确定它们的细胞功能，并确定与疾病相关的生物学途径。已识别的风险变异体和途径是未来功能研究的重要前提，以阐明失弛缓症的生物学基础。此外，还将使用其他自身免疫性疾病的GWAS数据对失弛缓症GWAS数据进行联合分析。此外，还将使用失弛缓症Gwas数据和从患者收集的详细表型数据进行基因-表型(GxP)研究。这些数据将有助于估计失弛缓症和其他自身免疫性疾病之间的遗传相关性，以及识别基于生物学的失弛缓症亚型。所应用的项目并没有随着全球气候变化网络的建立而结束。通过我们自己的工作，并与其他科学家合作，将对识别的风险变异进行功能分析，这将有助于阐明贲门失弛缓症的病理生理机制。

Idiopathic achalasia represents a primary motility disorder of the esophagus. It is characterized by esophageal aperistalsis and a failure of the lower esophageal sphincter (LES) to relax due to a loss of inhibitory neurons in the myenteric plexus. Although the pathophysiology of this neuronal degeneration is mainly unknown, autoimmune processes seem to be involved in individuals with a genetic susceptibility. On the etiology level, achalasia is multifactorial and involves a combination of the cumulative effect of variants in various risk genes and environmental factors. Recently, we have conducted the first systematic association studies in case control samples with achalasia using the Illumina ImmunoChip that contains > 190 K single nucleotide polymorphisms (SNPs) in genomic regions that previously showed association to various autoimmune diseases. This revealed that an 8-amino-acid insertion in the cytoplasmic tail of the HLA-DQ receptor confers the strongest risk for achalasia (Gockel et al. (2014) Nat Genet 46: 901-904). Furthermore, two amino acid substitutions in the extracellular domain of the HLA-DQ receptor independently confer achalasia risk. In addition, we have shown that the 8-amino-acid insertion in the HLA-DQ receptor is less common in Northern compared to Southern Europeans (Becker et al. (2016) Eur J Hum Genet 24: 1228-1231). This geospatial north-south gradient implies that the prevalence of idiopathic achalasia may differ among populations. The aim of this project is the comprehensive identification of further genetic risk variants for idiopathic achalasia. For this purpose, a genome-wide association study (GWAS) will be carried out using 5,000 European patients as well as 6,346 ethnically matched controls. Identified risk variants will be followed up by in silico functional studies in order to determine their cellular function and to identify disease relevant biological pathways. The identified risk variants and pathways represent important prerequisites for future functional studies in order to elucidate the biological basis of achalasia. In addition, the achalasia GWAS data will be analyzed jointly using GWAS data for other autoimmune diseases. Furthermore, genotype-phenotype (GxP) studies will be carried out using the achalasia GWAS data and detailed collected phenotypic data from patients. These data will allow to estimate the genetic correlation between achalasia and other autoimmune disorders as well as the identification of biologically based subtypes of achalasia. The applied project does not end with the GWAS. By our own work and in cooperation with other scientist, the identified risk variants will be functionally analyzed, which will help to elucidate the pathophysiology of achalasia.