Association between rs12970134 Near MC4R and adiposity indexes in a homogenous population of Caucasian schoolchildren.

BACKGROUND: To assess whether previously identified obesity-susceptibility loci were associated with overweight/obesity risk in a homogeneous population of Caucasian schoolchildren and whether these associations varied with age. METHODS: Seven hundred and forty-five schoolchildren (353 boys, mean age: 8.3 ± 1.4 years) underwent anthropometric assessments. A saliva sample was collected for DNA extraction and assessment of 19 single-nucleotide polymorphisms previously associated with obesity. RESULTS: Only the rs12970134 in the MC4R gene was significantly associated with overweight/obesity risk, with a higher frequency of the AA risk genotype in children with a BMI >85th (8.3%) than in those with a BMI <85th percentile (3.0%), p = 0.001; odds ratio (95% CI) of 1.544 (1.192-1.998), p = 0.001, after adjusting for age, sex and pubertal stage. BMI standard deviation scores (SDS) and waist-to-height ratio (W/Hr) progressively increased across the rs12970134 genotypes (GG vs. AG vs. AA): BMI SDS, p = 0.004; W/Hr, p = 0.009. When dividing the study population into two groups based on the median age of participants (8.3 years), the differences in BMI SDS and W/Hr across the MC4R genotypes persisted only in children older than 8.3 years. CONCLUSIONS: In a population of Caucasian schoolchildren, the rs12970134 MC4R variant was significantly associated with excess body weight, particularly in children older than 8 years of age.