Association of epigenetic differences nominated by monozygotic twins discordant for attention-deficit hyperactivity disorder with their brain structures

The present study examined the relationship between genome-wide methylation differences and variations in brain structures involved in the development of attention-deficit hyperactivity disorder (ADHD). We used monozygotic twins discordant for ADHD to identify candidate DNA methylation sites involved in the development of ADHD. Two pairs of MZ twins discordant for ADHD were recruited from the Department of Child and Adolescent Psychological Medicine at the University of Fukui Hospital. The twins were 9-year-old males (pair 1) and 16-year-old females (pair 2). Genomic DNA was collected from saliva samples, and the DNA was then whole-genome amplified, fragmented, and hybridized to the Human MethylationEPIC BeadChip. Bisulphite converted saliva DNA from the 4 samples (2 monozygotic twins discordant for ADHD) were hybridized to the Illumina Infinium Methylation EPIC Kit array