Genetic susceptibility to obesity and related traits in childhood and adolescence: influence of loci identified by genome-wide association studies

OBJECTIVE--Large-scale genome-wide association (GWA) studies have thus far identified 16 loci incontrovertibly associated with obesity-related traits in adults. We examined associations of variants in these loci with anthropometric traits in children and adolescents. RESEARCH DESIGN AND METHODS--Seventeen variants representing 16 obesity susceptibility loci were genotyped in 1,252 children (mean ± SD age 9.7 ± 0.4 years) and 790 adolescents (15.5 ± 0.5 years) from the European Youth Heart Study (EYHS). We tested for association of individual variants and a genetic predisposition score (GPS-17), calculated by summing the number of effect alleles, with anthropometric traits. For 13 variants, summary statistics for associations with BMI were meta-analyzed with previously reported data ([N.sub.total] = 13,071 children and adolescents). RESULTS--In EYHS, 15 variants showed associations or trends with anthropometric traits that were directionally consistent with earlier reports in adults. The meta-analysis showed directionally consistent associations with BMI for all 13 variants, of which 9 were significant (0.033-0.098 SD/allele; P < 0.05). The near-TMEM18 variant had the strongest effect (0.098 SD/allele P = 8.5 x [10.sup.-11]). Effect sizes for BMI tended to be more pronounced in children and adolescents than reported earlier in adults for variants in or near SEC16B, TMEM18, and KCTD15, (0.028-0.035 SD/allele higher) and less pronounced for rs925946 in BDNF (0.028 SD/allele lower). Each additional effect allele in the GPS-17 was associated with an increase of 0.034 SD in BMI (P = 3.6 x [10.sup.-5]), 0.039 SD, in sum of skinfolds (P = 1.7 x [10.sup.-7]), and 0.022 SD in waist circumference (P = 1.7 x [10.sup.-4]), which is comparable with reported results in adults (0.039 SD/allele for BMI and 0.033 SD/allele for waist circumference). CONCLUSIONS--Most obesity susceptibility loci identified by GWA studies in adults are already associated with anthropometric traits in children/adolescents. Whereas the association of some variants may differ with age, the cumulative effect size is similar. Diabetes 59:2980-2988, 2010
Over the past three decades, the prevalence of obesity has reached epidemic proportions not only in adults, but in children and adolescents alike (1,2). A high BMI during childhood and [...]