Sex‐specific association between leptin receptor polymorphisms and leptin levels and BMI in healthy adolescents

Aim:  To examine the relationship of three common polymorphisms in the leptin receptor (LEPR) gene, implicated in the regulation of body weight, with leptin levels and obesity-related phenotypes in a population-based sample of healthy pubertal children in Spain. Methods:  The study included 806 boys and girls aged 12–16 whose anthropometrical data and body composition were recorded. Serum leptin levels were determined by ELISA. The LEPR Q223R, K109R and K656N polymorphisms were determined by TaqMan® allelic discrimination assays. Results:  When analysing the Q223R polymorphism, we observed that female carriers of the RR genotype had significantly higher plasma leptin levels (18.2 vs. 15.1 ng/mL p = 0.016) and significantly higher mean BMI values (22.5 vs. 21.3 Kg/m2 p = 0.032) than QR carriers. Furthermore, the frequency of the RR genotype in overweight-obese girls was significantly higher than that found in normal-weight girls. No significant differences were observed in boys. Neither boys nor girls showed significant differences when comparing leptin levels, anthropometric variables or body composition by K109R or K656N genotype. Conclusion:  The fact, that the Q223R polymorphism in the LEPR gene is significantly associated with leptin levels and BMI only in girls, suggests a sex-specific influence of this polymorphism on these variables.