Our findings on the changes in DNA methylation at the Mecp2 REs are in agreement with the previous reports on MECP2 promoter methylation, which demonstrate that an approximate difference of 2.0 to 2.5% overall methylation over a region -233 to -531 upstream of the MECP2 promoter is correlated with reduced MECP2 expression in autistic male brains. The authors report that within the 15 CpG sites found in this MECP2 promoter region, two CpG sites are specifically altered in the autistic males [2]. Furthermore, our results are in agreement with a previous report on significantly reduced MeCP2 expression in the postnatal mouse brain (under stress), which is associated with 2 to 5% increased methylation at the individual CpG sites within a 164-bp region of the Mecp2 promoter [20]. Supporting these observations, studies have also shown minor differences, such as 2 to 5% DNA methylation causing significant changes in the expression of other genes, such as RASSF1, in the human brain [66], AMOTL2 in the human heart [67], and PGC1α in human muscles [68]. Therefore, although the detected DNA methylation changes in
