Association between Two Common Missense Substitutions, Thr6Lys and Val81Ile, in MC3R Gene and Childhood Obesity: A Meta-Analysis.

BACKGROUND

Two common missense variants in the melanocortin-3 receptor (MC3R) gene, Thr6Lys (T6K) and Val81Ile (V81I), are presumably correlated with pediatric obesity. This meta-analysis aimed to examine and synthesize evidence on the association between these two common MC3R polymorphisms and the development of childhood obesity.

METHODS

A combination of words relevant to the research question was searched on PubMed, EMBASE, Scopus, and the Cochrane database. Results were restricted to human studies, specifically child and adolescent populations. Articles were excluded based on accessibility of full online texts and availability of pertinent data. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random effects model to determine the association of the polymorphisms with obesity.

RESULTS

Searches on the databases using the keywords identified 65 potentially relevant reports. Among them, 32 studies were excluded due to irrelevance, and 28 studies excluded due to lack of access, insufficient data, and investigation of other variants. A final set of five studies included in this meta-analysis found that the risk of overweight/obesity increased by 46.1% per K allele and 21.7% per I allele. Only homozygous genotypes for T6K were associated with a 3.10-fold (95% CI: 1.29-7.43) increased risk of overweight/obesity in children. Data were insufficient to examine if homozygosity for both rare alleles further increases risk.

CONCLUSIONS

Our results supported a recessive inheritance model for MC3R gene as a potential cause of childhood obesity. High clinical heterogeneity existed among studies and thus requires more research of larger participation for future integration of data.