RESUMO
BACKGROUND: FokI (rs2228570 T>C) and BsmI (rs1544410 A>G) polymorphisms of the vitamin D receptor (VDR) have been associated to abnormal glucose metabolism and could be inversely associated with ß-cell function (BCF) and vitamin D status. There is a lack of information about this topic in the Mexican population. AIM OF THE STUDY: To evaluate the relationship between VDR gene polymorphisms FokI and BsmI with BCF and vitamin D status in a population of non-obese Mexican adults. METHODS: A sample of 192 participants were enrolled during 2016-2018. Blood samples were collected to determine fasting concentrations of glucose, insulin, and vitamin D. Genomic DNA was isolated from leucocytes and the polymorphic variants of FokI and BsmI were analyzed. The Homeostasis Model Assessment Calculator was used to estimate the BCF (HOMA2-B). RESULTS: FokI polymorphism showed a frequency of 20.1% for homozygous TT carriers and 7.8% for the BsmI GG. The recessive model of FokI (TT genotype) showed a lower mean value of BCF compared to the combination of CC + CT (99.2 vs. 109.6%, p = 0.045). Likewise, significantly lower mean values of HOMA2-B and insulin were observed for BsmI (GG genotype, p = 0.016 and p = 0.039, respectively). After covariates adjustment, only FokI polymorphism remained as an independent predictor of BCF. CONCLUSIONS: the TT and GG variants of the FokI and BsmI polymorphisms are related to a decrease in FCB. In the case of FokI, this decrement was independent of insulin sensitivity, vitamin D levels, percentage of body fat, gender, and age.
Assuntos
Insulinas , Receptores de Calcitriol/genética , Adulto , Estudos de Casos e Controles , Predisposição Genética para Doença , Genótipo , Humanos , Polimorfismo Genético , Polimorfismo de Nucleotídeo Único , Vitamina DRESUMO
Aside from the admixture between indigenous people and people from overseas, populations in Mexico changed drastically after the Spanish conquest of the sixteenth century, forming an intricate history that has been underutilized in understanding the genetic population structure of Mexicans. To infer historical processes of isolation, dispersal, and assimilation, we examined the phylogeography of mitochondrial (mt) DNA and Y-chromosome lineages in 3,026 individuals from 10 urban and nine indigenous populations by identifying single nucleotide polymorphisms. A geographic array with a predominance of Amerindian lineages was observed for mtDNA, with northern indigenous populations being divergent from the central and southern indigenous populations; urban populations showed low differentiation with isolation by distance. Y-chromosome variation distinguished urban and indigenous populations through the Amerindian haplogroup Q frequency. The MtDNA and the Y-chromosome together primarily distinguished urban and indigenous populations, with different geographic arrays for both. Gene flow across geographical distance and between the urban and indigenous realms appears to have altered the pre-Hispanic phylogeography in central and southern Mexico, mainly by displacement of women, while maintaining the indigenous isolation in the north, southeast, and Zapotec regions. Most Amerindian mtDNA diversity currently occurs in urban populations and appears to be reduced among indigenous people.