Supplementary Material for: Genetic Variants in the Activation of the Brown-Like Adipocyte Pathway and the Risk for Severe Obesity

<b><i>Background:</i></b> Regular physical activity has an important role in energy expenditure and combats the development of obesity. During exercise, <i>PPARGC1A</i> is overexpressed, stimulating an increase of the expression of <i>FNDC5</i>. This protein is cleaved to release the hormone irisin, which activates a browning process in white adipose tissue through an increase in <i>UCP1</i> expression. As a result, irisin leads to mitochondrial heat production and energy expenditure. <b><i>Objectives:</i></b><i></i>The aim of this study was to investigate whether genetic variants in genes related to browning are associated with severe obesity and obesity-related features. This case-control study comprised 210 individuals with severe obesity (median body mass index [BMI] 45.6 [range 40.5–52.2]) and 191 normal-weight subjects (BMI 22.8 [21.1–23.9]). <b><i>Methods:</i></b> Genomic DNA was extracted from peripheral blood and the genotypes of the <i>PPARGC1A</i>(rs8192678, rs3736265, rs2970847, and rs3755863) and <i>UCP1</i> (rs6536991 and rs12502572) genes were obtained using Taqman® assay. For the <i>FNDC5</i> gene, screening of exons 3–5 as well as their intron-exon boundaries was performed using automatic sequencing. <b><i>Results:</i></b> Our results demonstrated that <i>PPARGC1A</i>rs2970847 and <i>UCP1</i>rs12502572 are associated with severe obesity. Furthermore, these polymorphisms influence anthropometric traits, such as BMI, body weight, and body adiposity index. Our findings also showed a dose-effect relationship between <i>PPARGC1A</i> rs8192678 and fasting plasma glucose. Finally, 5 rare mutations were identified in <i>FNDC5</i>, and 1 of these is a novel missense mutation. <b><i>Conclusion:</i></b> This study shows that genetic variants in the activation of brown-like adipocyte pathway play an important role in the susceptibility to severe obesity.

**背景：** 规律体育运动在能量消耗中发挥关键作用，可对抗肥胖的发生发展。运动过程中，过氧化物酶体增殖物激活受体γ辅激活因子1α（PPARGC1A）表达上调，可促进纤连蛋白Ⅲ型结构域包含蛋白5（FNDC5）的表达增加。该蛋白经切割后释放出鸢尾素（irisin）这一激素，鸢尾素可通过上调解偶联蛋白1（UCP1）的表达，激活白色脂肪组织的褐变过程。最终，鸢尾素可促进线粒体产热并增加能量消耗。
**研究目的：** 本研究旨在探究与脂肪褐变相关的基因的遗传变异是否与重度肥胖及肥胖相关表型存在关联。本项病例对照研究共纳入210例重度肥胖受试者（体重指数[BMI]中位数为45.6，范围40.5~52.2）以及191例体重正常受试者（BMI为22.8，范围21.1~23.9）。
**研究方法：** 从外周血中提取基因组DNA，采用Taqman®探针法对PPARGC1A基因的rs8192678、rs3736265、rs2970847及rs3755863位点，以及UCP1基因的rs6536991和rs12502572位点进行基因分型。针对FNDC5基因，采用自动测序技术对其第3~5外显子及内含子-外显子剪接边界区域进行筛查。
**研究结果：** 本研究结果显示，PPARGC1A基因rs2970847位点与UCP1基因rs12502572位点均与重度肥胖存在关联。此外，上述多态性位点可影响人体测量学指标，包括BMI、体质量及体脂指数。本研究同时发现，PPARGC1A基因rs8192678位点与空腹血糖存在剂量效应关系。最终，在FNDC5基因中共检出5处罕见突变，其中1处为全新的错义突变。
**研究结论：** 本研究证实，棕色样脂肪细胞激活通路相关的遗传变异在重度肥胖的易感性中发挥重要作用。