Functional and Multi-Ethnic Fine-Mapping of Serum Urate/Gout Loci

描述（由申请人提供）： 全球尿酸盐遗传学联盟已经验证了血清尿酸盐中的28个SNP关联。其中一些位点含有尿酸盐转运蛋白基因，而大多数其他位点的致病基因仍然没有得到解决。GWAS发现了与因果变异相关的统计学连锁不平衡的SNP，而不是因果变异本身。需要了解致病变异、它们的作用机制以及与其他基因座的相互作用，以确定致病基因。这将导致对导致高尿酸血症和痛风的功能障碍的精确生物学的理解，并将确定新的治疗靶点。我们建议在血清尿酸盐位点进行精细定位和因果变异分析，并对强候选功能变异进行集中功能测定。 在样本采集，数据生成和统计分析的进步创造了机会，以精细地图尿酸盐基因座在多个种族，一个功能，pupestrian因果变异的等位基因谱的特点。我们将利用欧洲人、非裔美国人、西班牙人/拉丁美洲人和波利尼西亚人祖先的三个血清尿酸盐/痛风队列，其不同的连锁不平衡模式将促进尿酸盐/痛风的定位。 遗传信号（总N > 5，000）。遗传数据包括跨血清尿酸盐基因座的靶向下一代基因序列，以及具有1000个基因组插补的GWAS和外显子组芯片基因型，其代表常见变体和候选基因编码区的低频变异的序列水平数据。低频变体对于功能随访特别感兴趣，因为它们预期具有更大的效应大小。我们建议进行跨队列的荟萃分析，并联合跨种族贝叶斯推断的“可信集”的因果变异。注释、生物信息学和功能基因组数据将被纳入贝叶斯框架中变异的先验概率中。一个优先的“可信的因果变异集”将是这个项目的初步成果。 在血清尿酸盐和高尿酸血症中，稳健且廉价的功能模型可用于测定尿酸盐转运中候选致病变体的功能后果，从而验证和表征作用机制（例如，尿酸盐转运增加vs减少）。在目标2中，我们建议使用非洲爪蟾卵母细胞中的尿酸盐转运来表征特定尿酸盐转运蛋白的最高优先级推定致病变体的功能影响。这些实验将验证并协同上述遗传分析。除了尿酸转运蛋白编码变体，我们还可以通过在卵母细胞中共表达直接相互作用的蛋白质并测量对尿酸转运的影响来测定它们。该项目将提供一组血清尿酸盐致病变异体的体外功能结果。

DESCRIPTION (provided by applicant): The Global Urate Genetics Consortium has validated 28 SNP associations in serum urate. Some of these loci harbor urate transporter genes, whereas for most other loci the causal genes remain unresolved. GWASdiscovers associated SNPs in statistical linkage disequilibrium with causal variants, not the causal variants themselves. Knowledge of the causal variants, their mechanisms of action, and interactions with other loci are needed to pinpoint the causal genes. This will lead to understanding of the precise biology of dysfunction leading to hyperuricemia and gout, and will identify new therapeutic targets. We propose to conduct fine-mapping and causal variant analyses in the serum urate loci, and to conduct focused functional assays of strong candidate functional variants. Advances in sample acquisition,data generation and statistical analysis create the opportunity to fine-map urate loci in multiple ethnicities, an to characterize the allelic spectrum of functional, putatively causal variation. We will utilize tree serum urate/gout cohorts of European, African American, Hispanic/Latino and Polynesian ancestries, whose differing patterns of linkage disequilibrium will facilitate the localization of genetic signal (total N > 5,000). The genetic data include targeted next- generation sequence of genes across the serum urate loci, and GWAS and Exome-chip genotypes with 1000 Genomes imputation, representing sequence-level data for common variants and for low- frequency variation for coding regions of candidate genes.Low-frequency variants are of particular interest for functional follow up, since they are expected to have larger effect sizes.Here, in Aim 1, we propose to conduct meta-analysis across cohorts, and joint cross-ethnic Bayesian inference of the 'credible set' of causal variants. Annotation, bioinformatic and functional genomic data will be incorporated into variants' prior probabilities in the Bayesian framework.A prioritized 'credible set' of causal variants will be the prima facie deliverable of this project. In serum uate and hyperuricemia, robust and inexpensive functional models can be used to assay the functional consequences of candidate causal variants in urate transport, and therefore to validate and characterize the mechanism of action (e.g. increased vs decreased urate transport). In Aim 2, we propose to useurate transport in Xenopus oocytes to characterize the functional impacts of the highest-priority putative causal variants for specific urate transporter. These experiments will validate and synergize with the genetic analyses described above. In addition to urate transporter coding variants, we can assay directly interacting proteins by co-expressing them in oocytes and measuring effects on urate transport. This project will deliver ex vivo functional consequences of a set of serum urate causal variants.