Análise do perfil epigenético de crianças com fendas labiopalatinas não sindrômicas

Abstract

Non-syndromic clefts of the lip and/or palate (NSCL/P) are birth defects arising from environmental and genetic causes. Recent studies have linked epigenetic factors, such as DNA methylation, to the inheritability of this complex malformation, as well as nutrition has been considered an environmental trigger of NSCL/P acting directly on the methylation profile. Thus, the aim of this work was to analyze the epigenetic pattern of children with NSCL/P. The dietary pattern of oral clefts children and the gestational exposure profile of their mothers were also investigated. Buccal mucosa cells were collected from all children for DNA extraction and for global and specific methylation determination. For this, the bisulfite restriction analysis (COBRA) technique was performed to the 5-methylcytosines (5-mC) of LINE-1 and Alu regions since they comprise about 30% of the human genome, in addition, the polymerase chain reaction was performed to analyze the specific methylation of BRCA1 promoter. The choice of this gene was based on its role in genome stability. In addition, the mothers collaborated answering a questionnaire about their exposure factors during pregnancy and their children dietary information. As a result, the control group showed a higher consumption of "ultraprocessed", "refined wheat", "processed vegetable fats", "simple carbohydrates" and "sausages" (p <0.05), but for the other food categories there was no statistical difference between groups. Regarding the gestation data, a low gestational programming rate was observed and consequent delay in the beginning of nutritional supplements use that support a proper embryo development. In addition, contraceptive use time prior to gestation was significantly higher for mothers in the clefts group and it was associated with a nearly two-fold increased risk for non-syndromic oral clefts (p = 0.036, 95% CI= 0.639–4.134). About the global DNA methylation, it was found a mean LINE-1 5-mC of 48% and 45.3% for control and clefts group, respectively, with significant statistical difference (p = 0.047). The BRCA1 promoter was methylated in 30.4% and 56.5% of control and clefts subjects, respectively, with no statistical difference between groups. In general, it was seen a poor quality dietary profile of the research participants and there was a higher tendency to global hypomethylation and BRCA1 hypermethylation in children with clefts. These findings corroborate with recent speculations that DNA methylation may be the result of a transgenerational epigenetic inheritance and it have effects on the etiology of this malformation. Further studies are needed to confirm these findings and to understand other epigenetic mechanisms that are acting in conjunction with the genetic susceptibility variants and as a consequence of the environmental factors responsible for this phenotype characterization.