According to the results the genomic regions harboring DNA methylation marks were statistically significantly enriched (q-value ≤ 5.00E-02) for alleles in linkage disequilibrium with single nucleotide polymorphisms, which have been previously associated with attention deficit disorder with hyperactivity (ADHD), monocyte chemoattractant protein 1 (MCP1) level, bipolar disorder and in the mental disorder trait class (Table 2). Here, CCL2 is linked to attention deficit-hyperactivity disorder.