Interaction of environmental factors with the polygenic risk scores of thinness-related genes in preventing obesity risk in middle-aged adults: The KoGES.

Abstract

Some persons are genetically resistant to obesity, but only a few studies have evaluated thinness genes for preventing obesity. We aimed to investigate the association of polygenic variants with being underweight and their interaction with the lifestyles of middle-aged and elderly persons and identify potential new genetic approaches for managing body weight. In total, 58,701 participants aged 40-77 years were recruited from urban hospitals in Korea. Underweight (case) was defined as body mass index (BMI) < 18.5 kg m2 (n = 991) and normal weight (control, n = 21,921) was defined as 18.5 ≤ BMI < 23 kg m2 . A genome-wide association study was run to identify thinness-related single nucleotide polymorphisms (SNPs) after adjustment for compound factors using Gplink. The generalised multifactor dimensionality reduction program was used to identify the genetic variants with SNP-SNP interactions. The polygenic risk score (PRS) was calculated by summing up the number of risk alleles in each SNP and classifying them into low-, medium- and high-PRS. The best model included the ANK2_rs7656666, CAST_rs28042, SLC1A3_rs928431867, CHST12_rs2906173, ALOX5_rs1051713, RGS6_rs17180754, ST8SIA5_rs79491311 and DCC_rs35721894 alleles. The participants with high-PRS had a lower BMI (p < 0.0001) than those with low-PRS and were 3.834 (2.58-5.70) times more likely to be underweight after multivariate adjustment (p < 0.001). The selected SNPs were correlated with each other and highly expressed in brain-related genes. The genes with minor alleles of CAST_rs28042 and CHST12_rs2906173 exhibited a higher expression frequency in brain-related tissues. PRS had significant interactions with protein, sodium, indigestible carbohydrates, calcium intake and exercise (p < 0.05), influencing the underweight state. People with a high-PRS were more underweight than those with low-PRS under high protein, sodium, high calcium, low indigestible carbohydrate intake and low exercise by 3.75, 3.88, 7.05, 3.18 and 3.80 times, respectively (p < 0.0001). In conclusion, adults having a high-PRS were significantly correlated with being underweight, especially in combination with a particular nutritional status. These results show the potential for thinness genes to be applied to personalised nutrition for preventing obesity through targeted gene therapy.