The common link between our study and previously published human GWAS studies is the role of epigenetics in regulating the expression of key genes/associated loci by MECP2, which is a DNA methylation protein implicated in Rett syndrome (Amir et al., 1999), autism (Loat et al., 2008), mental retardation (Shahbazian and Zoghbi, 2001), and mild learning disabilities (Shibayama et al., 2004). This evidence concerns the gene MECP2 and Rett syndrome.