Loci identified in genome-wide association studies (GWAS) can include multiple distinct association signals. We sought to identify the molecular basis of multiple association signals for adiponectin, a hormone involved in glucose regulation secreted almost exclusively from adipose tissue, identified in the Metabolic Syndrome in Men (METSIM) study. With GWAS data for 9,262 men, four loci were significantly associated with adiponectin: ADIPOQ, CDH13, IRS1, and PBRM1. We performed stepwise conditional analyses to identify distinct association signals, a subset of which are also nearly independent (lead variant pairwise r²<0.01). Two loci exhibited allelic heterogeneity, ADIPOQ and CDH13. Of seven association signals at the ADIPOQ locus, two signals colocalized with adipose tissue expression quantitative trait loci (eQTLs) for three transcripts: trait-increasing alleles at one signal were associated with increased ADIPOQ and LINC02043, while trait-increasing alleles at the other signal were associated with decreased ADIPOQ-AS1. In reporter assays, adiponectin-increasing alleles at two signals showed corresponding directions of effect on transcriptional activity. Putative mechanisms for the seven ADIPOQ signals include a missense variant (ADIPOQ G90S), a splice variant, a promoter variant, and four enhancer variants. Of two association signals at the CDH13 locus, the first signal consisted of promoter variants, including the lead adipose tissue eQTL variant for CDH13, while a second signal included a distal intron 1 enhancer variant that showed ~2-fold allelic differences in transcriptional reporter activity. Fine-mapping and experimental validation demonstrated that multiple, distinct association signals at these loci can influence multiple transcripts through multiple molecular mechanisms.

在全基因组关联研究 (GWAS) 中识别的位点可以包括多个不同的关联信号。我们试图确定脂联素多重关联信号的分子基础，脂联素是一种参与葡萄糖调节的激素，几乎完全由脂肪组织分泌，在男性代谢综合征 (METSIM) 研究中发现。根据 9,262 名男性的 GWAS 数据，四个位点与脂联素显着相关：ADIPOQ、CDH13、IRS1和PBRM1。我们进行了逐步条件分析以识别不同的关联信号，其中的一个子集也几乎是独立的（导致变体成对 r ² <0.01）。两个位点表现出等位基因异质性，ADIPOQ和CDH13。在ADIPOQ基因座的七个关联信号中，两个信号与三个转录本的脂肪组织表达数量性状基因座 (eQTL) 共定位：一个信号的性状增加等位基因与ADIPOQ和LINC02043增加相关，而另一个信号的性状增加等位基因与ADIPOQ-AS1降低有关。在报告分析中，两个信号的脂联素增加等位基因显示了对转录活性影响的相应方向。七个ADIPOQ信号的推定机制包括错义变体 ( ADIPOQG90S)、一个剪接变体、一个启动子变体和四个增强子变体。在CDH13基因座的两个关联信号中，第一个信号由启动子变体组成，包括CDH13的主要脂肪组织 eQTL 变体，而第二个信号包括远端内含子 1 增强子变体，其显示转录报告基因活性的~2 倍等位基因差异. 精细定位和实验验证表明，这些基因座处的多个不同关联信号可以通过多种分子机制影响多个转录本。