| Summary: | 博士 === 國防醫學院 === 生命科學研究所 === 106 === Introduction
Globesity (global obesity) is one of the most important public health issues today. And morbid obesity (MO; body mass index, BMI≥35 kg/m2), an extreme phenotype of obesity, is becoming an emerging health issue worldwide. This is the first study to assess the prevalence trend of MO and unveil the environmental and genetics characteristics of MO in Taiwanese population.
Methods
Via three waves of Nutrition And Health Survey In Taiwan (1993-1996, 2005-2008, and 2013-2016), prevalence trend was available from national representative samples (3,071, 1,673 and 3,088). Next, using the same data, we conducted the gender and age (±3 years) matched case-control study with 39 MO cases (BMI≥35 kg/m2) and 156 normal BMI controls (18.5-24 kg/m2) to investigate the obesogenic environmental characteristics. The reduced rank regression analysis was used to find dietary pattern associated with MO. And then, we conducted a two stage genome-wide association studies (GWAS) with 553 MO cases from Minimally Invasive Surgery center of Min-Sheng General Hospital and 1,729 controls from Taiwan Han Chinese Cell and Genome Bank in the first stage; and independent 443 MO cases from Min-Sheng General Hospital and 9,237 controls from Taiwan Biobank in the second stage. PLINK software was used for GWAS analysis of the 1st, 2nd, and joint analysis.
Results
Within two decades, the prevalence trend of obesity (BMI≥27 kg/m2) (11.8 %, 17.9 %, to 23.0 %) and MO (BMI≥35 kg/m2) (0.4 %, 0.6 %, to1.3 %) increased sharply. MO cases tended to have lower levels of education, personal income, and physical activity. Furthermore, their dietary pattern featured with a higher consumption frequency of red meat, processed animal products, and sweets/sweetened beverage, but lower frequencies of fresh fruits, nuts, breakfast cereal, and dairy products.
According to the joint analysis of the 2 stage GWAS, we identified 5 loci with two or more significant (FDR p-value≤0.05) SNPs, including FTO (rs8050136, rs9939609, rs1421085, rs9941349, rs9937354, rs1121980, and rs7186521), RBFOX1 (rs12925846, rs17235335, and rs7201125), C8orf37-AS1 (LOC100616530) (rs3104994 and rs3104999), CTB-118N6.3/SEMA6A (rs258019 and rs34971) and RP11-638L3.1 (rs2126015 and rs76010193), are the important genetic markers for both MO and BMI. In addition, these 5 loci may lead to early-onset time and severe forms of obesity in Taiwan Han Chinese.
Conclusion
This study documents a phenomenon of BMI distribution shifting toward to higher proportions of obesity and MO. And MO was associated with low socioeconomic status, physical activity, and poor dietary pattern. In addition, obesogenic genetic characteristics, including the most frequently replicated genetic variant (FTO gene) of BMI, may also contribute to MO in Taiwanese. Further studies on interaction between genes (i.e. FTO gene) and obesogenic environment on MO etiology is urgently needed.
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