Evolutionary Significance of DNA Methylation in Human and Chimpanzee Brains

We compared the genome-wide patterns of DNA methylation in the brains of humans to those of our closest evolutionary relative, chimpanzees, using base-pair resolution whole-genome methylation maps of the prefrontal cortex. Our data reveal that the prefrontal cortex is the most heavily methylated among the human tissues examined so far. Nevertheless, hundreds of genes exhibit dramatically reduced levels of promoter DNA methylation in the human brain relative to the chimpanzee brain. Many of these genes are associated with neurological disorders, psychological disorders, and cancers, and are enriched for functions related to cellular metabolic processes and protein binding. Moreover, the majority of these genes exhibit higher expression in the human brain compared to the chimpanzee brain. Profiling DNA methylation map in prefrontal cortex regions of postmortem brains of three humans and three chimpanzees