SGCG rs679482 Associates with Weight Loss Success in Response to an Intensively Supervised Outpatient Program

Weight loss in response to energy restriction is highly variable and identification of genetic contributors can provide insights into underlying biology. Leveraging 1000 Genomes imputed genotypes we carried out GWAS analysis in 551 unrelated obese subjects of European ancestry who participated in an intensively supervised weight loss program with replication of promising signals in an independent sample of 1,331 obese subjects who completed the program at a later date. By SNP-based and sib-pair analysis, we show that that weight loss is a heritable trait with estimated heritability (h²=0.49) within the range reported for obesity. We find rs679482, intronic to SGCG (sarcoglycan gamma), highly expressed in skeletal muscle, to concordantly associate with weight loss in discovery and replication samples reaching GWAS significance in the combined meta-analysis (ß=-0.35, P=1.7×10^-12). Located in a region of open chromatin, rs679482 is predicted to bind DMRT2 and allele-specific transcription factor binding analysis indicates preferential binding of DMRT2 to rs679482-A. Concordantly, rs679482-A impairs native repressor activity and increases basal and DMRT2 mediated enhancer activity. These findings confirm that weight loss is a heritable trait and provide evidence by which a novel variant in SGCG, rs679482 leads to impaired diet response.