Relação das variantes genéticas do gene VDR com a hipovitaminose de marcadores do perfil glicêmico, lipídico, inflamatório, estresse oxidativo e antropométrico em adolescentes de escolas públicas no município de João Pessoa-PB

Abstract

Vitamin D is a pre-hormone with innumerable biological functions activated by vitamin D receptors (VDR) present in cells of the human body. Polymorphisms in the gene encoding this receptor may alter its concentration or cellular response to vitamin D, influencing glycemic and cardiovascular parameters such as dyslipidemias, high waist circumference, oxidative stress and inflammatory process. The objective of this study was to evaluate the relationship of BsmI and FokI polymorphisms in the VDR gene with hypovitaminosis D and markers for glycemic, lipidic, inflammatory, oxidative and anthropometric stress in adolescents of public schools. This is a transversal epidemiological study representative of students between 15 and 19 years, and involving 208 individuals. Anthropometric data and blood samples were collected for: DNA extraction; biochemistry (25-hydroxyvitamin D, parathyroid hormone, calcium, fasting glucose, total cholesterol, LDL-c, HDL-c and triglycerides); inflammatory markers (CRP-c-reactive protein and AGP- Alpha-1-acid glycoprotein); oxidative stress (MDA-malonaldehyde and TAC-total antioxidant capacity). Differences between genotype groups were tested by one-way ANOVA or its non-parametric correspondent Kruskal-Wallis test and post-test Dunn's. The logistic regression model was used for association between the genotyping patterns and the biochemical and anthropometric parameters. The variables with p<0.20 were subsequently adjusted for age, BMI and WC. Significance was adopted when p-value <0.05. Statistical analyses were carried out using the STATA 14 program (StataCorp; USA). A total of 78 boys and 130 girls with an average age of 17.7 (+1.14) years were evaluated. Half of the sample had insufficiency/deficiency of 25-hydroxyvitamin D. The allele frequency was 39.5% and 66.8% for B and F respectively, and 60.5% and 33.2% for b and f respectively. A significant relationship was observed between BsmI genotypes and blood glucose values (p=0.049), while the post-test showed significance in BBxbb (p=0.012) and Bbxbb (p=0.037). In the logistic regression analysis, glycaemia had a significant relation with the BB genotype (p=0.036; OR=2.15; CI95%=1.05-4.41), and in the cluster analysis BB+Bb (p=0.025; OR=1.89; CI95%=1.08-3.29) had a higher risk of glycemia above the median when compared to bb. On the other hand, in analyzing Bb+bb (p=0.025; OR=0.65; CI95%=0.46-0.93) in relation to BB, adolescents had a higher chance of having below-median glycaemia. This relationship did not occur in the FokI polymorphism. There was no association of polymorphism genotype distribution with anthropometric variables and lipid profile, inflammatory and oxidative stress markers. In the logistic regression analysis, only the A1GPA variable of the BsmI resulted in significance for the Bb genotype (p=0.039; OR=195; CI95%=1.03-3.66). The variables that resulted in p<0.20 for both polymorphisms were subsequently adjusted, and A1GPA remained significantly influential in the Bb heterozygote group (p=0.040; OR=2.02; CI95%=1.03-3.95); however, this was not considered relevant data considering that the other evaluated acute phase protein had no association. This study showed a significant relation of glycaemia in relation to the BsmI polymorphism genotype distribution; nevertheless, although some studies have found associations of VDR gene polymorphisms with cardiovascular risk factors in different populations, our study in healthy youths did not.