Evaluation of 9 gene variants in relation to obesity and anthropometric parameters in the Czech adolescent population

Abstract

Background: Genome-wide association studies have identified several gene variants associated with body mass index (BMI) and obesity so far. Objective and hypotheses: We performed a replication study of 9 previously reported variants in/near genes PCSK1 (rs6232, rs6235), BDNF (rs925946, rs4923461), SEC16B (rs10913469), TMEM18 (rs7561317), SH2B1 (rs7498665), KCTD15 (rs29941) and FTO (rs9939609) in the Czech adolescent population. We investigated their association with BMI status (underweight, overweight and obesity) and related anthropometric parameters. Methods: Genotyping was performed in 1443 adolescents, including 670 overweight/obese (BMI >=90th percentile), 713 normal weight (BMI 10-90th percentile) and 60 underweight (BMI <10th percentile) adolescents aged 13-18 years. Anthropometric parameters were assessed in all individuals. Results: FTO rs9939609 was associated with overweight and obesity (OR = 1.28, 95%CI 1.02-1.60, p = 0.04 and OR = 1.47, 95%CI 1.24-1.73, p < 0.001, respectively). This variant was associated with body weight, BMI, abdominal and hip circumference, body and trunk fat (p < 0.001). The minor allele of SEC16B rs10913469 increased risk of overweight/obesity (OR = 1.24, 95%CI 1.02-1.51, p = 0.04) and values of body weight, BMI, abdominal circumference and body fat (p < 0.05). The remaining variants had not significant odds ratios and only slight impact of the increasing number of risk alleles on body weight, BMI, abdominal and hip circumference, body and trunk fat was observed (p < 0.05). Interestingly, the risk G-allele of TMEM18 rs7561317 was negatively associated with underweight (OR = 0.56, 95%CI 0.36-0.88, p = 0.02). Conclusions: In addition to widely replicated FTO gene variant we confirmed the association of the SEC16B variant with overweight/obesity and related traits in our population sample. The risk variant of TMEM18 was not associated with obesity, but it seems to be protective against underweight.