A chemical that has not been given much thought and which has been understudied in the past has been found to be of great importance when it comes to understanding the brain structure of individuals with autism.
This chemical modification is believed to be abundantly present in the brains of many individuals diagnosed with autism.
Although the results of the study are in the preliminary stages and have yet to point to any conclusive evidence, they highlight pathways for new studies.
Experts say that the modification is a methyl group that attaches to a DNA base cytosine.
CPG Methylation is among the most intricately studied forms of DNA methylation. It targets Cytosines as well as Guanine. However, researchers have also found unusual patterns of CPG methylation in the brains of autistic individuals.
It should be noted that the new study is focused on Non-CPG methylation, in which the methyl group is said to stick to its Cytosines, which are further followed by their DNA bases.
Researchers highlight that these types of methylation are found mostly in the brains.
“This opens up new avenues of research that perhaps we haven’t considered carefully before,” says lead researcher, Dan Arking.
Dan Arking is an associate professor at Johns Hopkins University in Baltimore, Maryland in the field of genetic medicine.
Further, more efforts are being directed toward studying and understanding the role of DNA modifications in autistic individuals, which might assist researchers with the class of chemical modifications, says professor Hongjun Song.
Professor Hongjun Song heads the departments of neuroscience and neurology at Johns Hopkins. However, Professor Song is not involved in this study. “There’s a lot more Cytosines to look at in terms of methylation,” Song says, rather than solely those followed by a guanine.
Many genes have been found to reside in the regions of the genome that are linked to autism. The genome is also said to have a higher density of chemical tags.
For the purpose of the study, a post-mortem was conducted on the autistic brain. As expected, the results revealed a higher expression of genes that assist in removing methyl tags.
Researchers further discovered an inexpensive method which helps in the detection of methyl groups that are found next to the DNA base.
Although these methods are limited to 1 percent of the genomes, the parts are known to have a higher density of CPG’s.
Researchers further noticed in the brain tissue scans of 29 people diagnosed with autism as having doubled the tagged non-CPG tissues from 34 controls. Though these sites do not fall within autism genes, they cluster together in regulatory regions.
Excess non-CPG groups fall into a category called “beacons.”
Beacons are regions that are said to be rich in CPG sites and are present only in humans, and showcase traits that are unique to human beings.
Similarly, non-CPG methylation is also clustered and is also repetitive. These are thought to distinguish other primates from human beings.
“One could imagine that these may be the regions that are more relevant to phenotypes of autism, such as language deficits,” Arking says.