First, average level analysis considered the mean of all probes near each transcription start site and defined hypermethylation as being 1.3-fold higher than the genome-wide mean methylation ratio. Promoters with 1.3-fold lower DNA methylation levels were considered hypomethylated. This approach was intended to avoid distal nucleotide noise and focused on binding site for transcription factors, in order to be compared to other human studies. Results from this analysis noted a decrease in the diversity of methylated genes that occurred during differentiation. 1,143 genes changed in methylation status over differentiation. Ethanol prevented this change in 272 of those. More precisely, 344 genes change from moderate to either a hyper- or hypomethylation state. Ethanol prevented 97 genes from making this change, with 78 genes prevented from hypermethylation and 19 changed from hypomethylation to moderate status. Among the 78 genes where ethanol blocked hypermethylation, functional analysis showed that neuronal receptors were prominent. These patterns of DMRs indicate a widespread effect of ethanol on methylation during DRG differentiation.
