Epigenetics and Protective Factors in the Preterm Infant

The methylation status of target genes (BDNF, SLC6A4, OXTR, NR3C1) will be investigated. Cord blood will be collected at birth for PT and FT, only for PT a peripheral blood sample will be collected at hospital discharge, during routine clinical procedures. Genomic DNA will be extracted from aliquots of 0. 2 ml of each blood sample with the GeneElute Blood Genomic DNA kit (Sigma) and stored at -20°C. Aliquots of 250 ng of each DNA will be edited for methylation analysis with the EZ DNA Methylation Lightning kit (Zymo Research). Amplification of samples and their preparation for NGS sequencing will be performed. Samples will be sequenced on NextSeq 500 (Illumina). Individual processed sequences (PE reads) will be independently aligned to reference sequences using a parallel Smith-Waterman algorithm. Only reads that consistently align to the same reference sequence will be retained. At each CpG site in each analyzed sequence, the frequencies of the four bases will be evaluated.

Infants will undergo an MRI exam with a 3 Tesla Philips Achieva scanner and a 32-channel head coil. a trained experimenter will apply tactile stimulation associated with affective touch characteristics to the child with a soft brush on the right anterior tibial region in proximal and distal directions. The length of the stimulated area will be measured to cover approximately 15 cm, and tactile stimulations will be applied at a rate of 5 cm/s for 15s, with randomized intervals between stimuli of 10-15s (resulting in 5 stimulations in a 15s block). A regular audio signal will help the researcher to keep a constant stroke velocity. Audio commands will also be used to direct the experimenter. Infant must be asleep (natural sleep) during the fMRI acquisition.