Epigenetic Modifications Following Noxious Stimuli in Infants.

Abstract

To recruit healthy full- and preterm infants into genetic research and determine the effectiveness of a noninvasive DNA sampling technique for comparing epigenetic modifications. Noxious stimuli during a vulnerable period of infant neuronal plasticity may trigger long-term epigenetic changes affecting neurodevelopment, pain modulation, and reactivity. Recognizing epigenetic pain findings is problematic because parents are reluctant to enroll newborns into genetic research. Design: Within-subject change over time candidate-gene DNA methylation association study. Setting/ sample: Urban teaching hospital's neonatal intensive care unit and newborn nursery. Convenience sample of healthy full- (>37 weeks, n = 6) and preterm (<37 weeks, n = 6) infants. Parents participated in a genetic presentation prior to informed consent. Infant buccal saliva was collected after admission to the unit and prior to discharge. The methylation pattern at the 5' end of µ-opioid receptor gene ( OPRM1) was examined. DNA was treated with bisulfite to convert all cytosines to uracil residues, leaving methylated cytosines unchanged. Sequencing of untreated and bisulfite-converted DNA was carried out. The sequences of unconverted and bisulfite-converted DNA were aligned with ClustalW, fidelity of the polymerase chain reaction and the sequencing reaction evaluated, and the methylation pattern identified. Recruitment and assessment of a noninvasive DNA sampling technique for comparing epigenetic modifications were successful; however, infant stress did not produce a change in OPRM1 methylation expression. This study established the feasibility of recruiting healthy full-term infants into genetic research and the effectiveness of noninvasive DNA sampling for comparing epigenetic modification in infants.