Fig. 1: Chromosomal position of OXTR promoter region with corresponding DNA methylation levels (mothers).

Chromosomal position of all fragments of the OXTR CpG island for mothers are illustrated using graphical outputs generated by the UCSC Genome Browser (GRCh37/hg19; https://genome.ucsc.edu) and Geneious Prime 2020 software (https://www.geneious.com). The gene is presented in 5′ - > 3′ orientation from left to right. Amplicons are highlighted with respect to their genomic orientation. All CpG sites are illustrated with green bars, CpG island in light green (with CpG1 and CpG 188 labeled), MT2 area in blue, and exons in grey colour (transcription start site is marked by the red arrow). A region including several transcription factor binding sites for EGRI (OREG1492306 according to the UCSC Genome Browser; also known as NGFIA) is indicated in yellow. Common SNPs with a minor allele frequency >5% according to the UCSC Genome Browser are illustrated with pink bars. Genomic regions of OXTR SNPs that introduce, disrupt or shift methylation sites are highlighted (these CpG sites were excluded from statistical analyses). Boxplots showing DNA methylation across the investigated CpG sites. The box covers the DNA methylation data of each CpG site between the 25th to 75th quantile, the whiskers show the range of values falling within 1.5-fold the interquartile range. The horizontal line (red) represents the DNA methylation detection limit for targeted deep bisulfite sequencing (OXTR promoter: 1,96%). Note: ** The values in the range of amplicon 7 are not different due to epigenetic heterogeneity but rather due to technical variability.