Background/Aims: Obesity has increased rapidly in South African children and adolescents. Genes involved in appetite regulation have been extensively studied worldwide, but their role in the obesity phenotype in South African Black and mixed-ancestry school adolescents is unknown. Methods: Seven common polymorphisms in LEP, GHRL, CART and LEPR were analysed for genotype and haplotype association with anthropometric obesity phenotype indicators in South African Black and mixed-ancestry adolescent school learners. Results: The CART c.517A→G polymorphism was significantly associated with obesity susceptibility. The LEPR Lys109Arg G allele was associated with an average reduction of 2.36 kg/m2 in body mass index (BMI), 5.66 cm in waist circumference (WC) and 1.61 cm in mid-upper-arm circumference (MUAC). This was confirmed by haplotype analysis. Additionally, a haplotype of the LEP polymorphisms significantly increased BMI, MUAC and hip circumference, while LEPR haplotypes were associated with differences in MUAC. Conclusion: Our findings suggest that c.517A→G and Lys109Arg contribute to the variation in anthropometric obesity phenotype indicators observed among Black African and mixed-ancestry South African learners. Furthermore, haplotypes of LEP, LEPR and GHRL polymorphisms were associated with varying measurements of weight, BMI and WC. Further studies are required to confirm our results in a larger and homogeneous study population group.

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