ESPE Abstracts

Introduction: Obesity is a multifactorial disease resulting from an interplay between genetics and the environment. Metabolic, nutritional, psychosocial, and lifestyle factors participate, promoting various degrees of overweight or obesity. Pediatric obesity increases after infancy and is higher in early adulthood, showing a heritability of up to 85%. Genetic variants associated with BMI in children can exert their effects by affecting eating behavior, as is the case with single nucleotide polymorphisms (SNP) of the DRD2 gene. Patients who have the risk variation are more likely to have binge eating and hedonic disorders. The present study aimed to evaluate the allele and genotypic frequencies of the SNP rs6277 of the DRD2 gene in a pediatric population with obesity and their eutrophic controls.

Methodology: The case-control study enrolled 218 pediatric patients aged 5 to 16 years, 118 obese, and 100 eutrophics. In addition to the clinical evaluation, all participants underwent biochemical tests to measure the levels of fasting lipids, blood glucose, and insulin to calculate HOMA IR. DNA samples were extracted and genotyped by the real-time polymerase chain reaction method (real-time PCR).

Results: The risk allele (G) and the homozygous GG genotype were present in 57.6% and 36.4% of obese individuals and 54% and 29% of eutrophic individuals. Although the chi-square test was not significant for the distribution of the DRD2 polymorphism rs6277 genotypes among eutrophic and obese subjects, the Z-score for proportions of two populations was significant (0.00001; CI = 0, 05), indicating a tendency of the homozygous genotype for the risk allele (GG) to focus on the sample of the obese population. The comparison of the allelic and genotypic distribution carried out between the Metabolically Sick (OMD) and Obese Metabolically Healthy (WHO) subgroups were significantly different for the distribution of the genotypes (X2 = 5.860 and p = 0.053), with a predominance of the GG genotype among the OMD. The Odds Ratio was estimated for two or more cardiovascular factors between the groups, which resulted in an OR of 2.65 (CI = 1.016 to 3.682; p = 0.031) when the genotypes contained the risk allele.

Conclusion: The allelic and genotypic distribution proved to be significantly different from the distribution of the genotypes, with a predominance of GG among the metabolically ill obese. The A allele can be correlated with a protective effect in eutrophic individuals, despite its variation.

Keywords: pediatric obesity; DRD2 gene; polymorphisms; genotyping.