Exploring genetic markers of adult obesity risk in black adolescent South Africans—the Birth to Twenty Cohort

To date more than 90 loci that show an association with body mass index (BMI) and other obesity-related traits, have been discovered through genome-wide association studies. These findings have been widely replicated, mostly in European and Asian populations, but systematic investigation in African cohorts is still lacking. Therefore, the aim of our study was to replicate the association of six single-nucleotide polymorphisms (SNPs) previously linked to BMI, in a South African black adolescent cohort. The SNPs were in or near GNPDA2 (rs10938397), MTCH2 (rs10838738), NEGR1 (rs2568958), SH2B1 (rs7498665), STK33 (rs10769908) and TMEM18 (rs6548238). The SNPs were genotyped in 990 adolescents from the Birth to Twenty study, using an Illumina VeraCode assay, and association with BMI statistically assesed by using PLINK. Three of the SNPs tested were associated with BMI in this African cohort, and showed a consistent (albeit smaller) directional effect to that observed in non-African cohorts. We identified significant association between BMI and rs10938397 (effect allele-G) near GNPDA2 (P(adj)=0.003), rs7498665 (effect allele-G) in SH2B1 (P(adj)=0.014) and rs6548238 (effect allele-C) near TMEM18 (P(adj)=0.030). This data suggests that common genetic variants potentially contributes to obesity risk in diverse population groups.