Scientists have gone on a hunt through the DNA of some 10,000 families that have children with autism, in a lab at the Hospital for Sick Children in Toronto. In their study, they identified “genetic wrinkles” in DNA itself, which they trust could elucidate why some people find themselves on the autistic spectrum. They believe this is an essential new clue into how to diagnose autism spectrum disorder (ASD) early, or even treat it.
Co-author of the study released on Monday and director of the Centre for Applied Genomics at SickKids, Dr. Stephen Scherer, said that the discovery is “really quite exciting.” He also indicated that it unveils a whole new class of genes that they didn’t know (were) involved in autism before. He also added they do know that they are involved in brain function but don’t know how they fit into the jigsaw puzzle. This study estimates that genetic factors should be found in anywhere from 50 to 90 percent of individuals with ASD.
Scherer said that to dig deeper into these genetic components, the scholars had to “develop new methodologies.” Ryan Yuen developed a new computational approach nine years ago to allow him to Study for certain features within DNA itself, and compare patterns found within individuals with autism to their parents or “other controls in the population.” They have now revealed that sections of DNA from parents at times get doubled or tripled in their children. These are called tandem repeat expansions.
Yuen stated that Tandem replications are nucleotides, which are the building blocks of DNA, repeated adjacently, two or more times. The repeat can grow longer, when these wrinkled strands of DNA are replicated, which is why a tandem replication present in a parent’s DNA could be extended from parent to child. The higher these wrinkles are, the more likely that they could affect the gene function. Though it was difficult, Tandem repeats had been studied before individually, since they had to be studied for in one gene at a time. According to a press release from SickKids, tracing the tandem repeats that lead to ASD “would be like looking for a needle in a haystack,” as there can be a million tandem repeats in the genome.
Yuen also stated that in that research, they pioneered a method that can effectively search and analyze terabytes of whole-genome sequencing data for tandem repeat expansions. Yuen indicated that most of the genes linked to [these] repeats were never thought to be involved in autism before. He added that several of the new genes identified included those “involved in the nervous system,” and the location of the tandem repeat expansion in the DNA itself was associated with “certain characteristics and behaviors such as IQ and life skills.
Scherer on the other hand, stated that they identified about a million different sites across the vast expanse of the human genome that can expand and also contract. Scherer added that he thought the way they thought about this is the DNA in these regions is kind of like an accordion, and if they stretch out to some extent, the music that’s played by the DNA or by the instrument has a different tone to it. Scherer said that he’s been studying the autism spectrum in almost two decades.
This could be a boon for families and individuals with autism who want a key question answered as the discovery may lead to improved genetic tests. He added that all people with autism could also have serious medical conditions. Therefore, crucial information can be provided to the families and the health care providers after identifying new tandem replication expansions to paste into the genome and discover the other [genes] involved.