New understanding of genetics behind the autism spectrum
Autism is a spectrum, because it isn’t a clear-cut diagnosis — and because the brain is so complex — it has been hard to figure out what causes autism. This uncertainty has led rise to the anti-vaccination movement along with other groups who are at best misinformed and at worst trying to make a quick dollar. However, a new study reveals an important connection between dozens of genes that may contribute to autism, a major step toward understanding how brain development goes awry in some individuals with the disorder.
The research shows that CHD8, a gene that is strongly linked to autism, acts as a master regulator in the developing human brain and controls the expression of many other genes. Many of the genes it targets have also been implicated in the disorder, the researchers found.
“Strong genetic evidence has identified a set of regulatory genes as being important for autism risk.”
“But, it has been difficult to gain insight into the biological mechanisms that might be perturbed because we couldn’t functionally connect these genes with each other. Now, we can,” said Noonan, a member of the Kavli Institute for Neuroscience, and senior author of the study.
Recent studies have identified several dozen genes potentially associated with autism. In the past three years, the gene CHD8 has emerged as one of the strongest candidates. Individuals with a loss-of-function mutation in this gene, which inactivates the corresponding protein, are very likely to have an autism diagnosis.
CHD8 is thought to regulate gene expression by modifying the way DNA interacts with histones — proteins present in the nucleus of every cell that wind long strands of DNA like a spool. Until now, however, it has been unclear which genes CHD8 targets in the brain and whether these genes also play a role in autism.
By building out the network of genes regulated by CHD8, the researchers aim to understand which biological processes are disrupted by the harmful mutations in these genes that affect some individuals with the disorder.
To answer these questions, the team first identified sites in the genome that were bound by CHD8 in cells from the developing brains of humans and mice as well as cultured human neuronal stem cells. They found that CHD8 binds to thousands of targets in each tissue. Many of these binding sites were conserved across the two species, suggesting that CHD8 regulates genes that are broadly important for brain development in mammals.
Next, they looked to see whether CHD8 was regulating genes implicated in autism by previous genetic studies. They found that these autism-associated genes were more likely to be targeted by CHD8 than expected by chance, in both humans and mice.
To evaluate whether CHD8 directly regulated these other autism risk genes, the researchers reduced the expression of the CHD8 gene in cultured human neuronal stem cells and explored what, if any, gene expression levels changed. They found that depletion of CHD8 dysregulated many of its target genes; however, autism risk genes were most strongly affected.
“Our results really point to CHD8 as being a major regulator of a whole network of genes that are involved in autism,” said Justin Cotney, first author on the paper.
“What’s so exciting about these findings is that we can use these data to predict additional autism genes, which before we had limited power to do.”
The new study begins to simplify the complex web of genes that may be involved in autism by investigating the targets of genes that have been linked to the disorder in a systematic way. The researchers are currently investigating the regulatory roles of the genes targeted by CHD8 in brain tissue.
“We believe this will help reveal specific biological pathways and developmental processes that are affected in autism,” Noonan said.
This isn’t the only good news toward the understanding of autism, there is also a new blood test that may help screen for autism at a earlier age. Since time is a factor in helping an autistic child adjust to the world around them getting an early diagnosis and more importantly, understanding what that means for the child is important. You can read more about that here, or if you prefer the paper on the test, you can check the sources.
As per the usual here at Lunatic Laboratories, we encourage everyone to vaccinate your children because there has never been and never will be a link between any neurological disorder and vaccines. It can be scary when there is misinformation floating around and this can lead to the decision that doing nothing is better than potentially causing harm. I encourage anyone reading this that is on the fence about it to just read peer-reviewed research on the subject from actual journals.
Google scholar will help you find them if you are stuck and searching them is relatively easy. Abstracts will tell you the end result of the study along with the general methodology and as always, speaking to your Doctor about this will help ease fears. Vaccines are safe, effective, and will prevent unnecessary suffering, complications from illness, or even death.
You don’t have to take my word for it, the research is sound and speaks for itself. I am just encouraging anyone on the fence to find actual research and see for yourself, don’t trust some celebrity or random guy on the internet, that’s how phishing scams work.
Cotney, J., Muhle, R., Sanders, S., Liu, L., Willsey, A., Niu, W., Liu, W., Klei, L., Lei, J., Yin, J., Reilly, S., Tebbenkamp, A., Bichsel, C., Pletikos, M., Sestan, N., Roeder, K., State, M., Devlin, B., & Noonan, J. (2015). The autism-associated chromatin modifier CHD8 regulates other autism risk genes during human neurodevelopment Nature Communications, 6 DOI: 10.1038/ncomms7404
Pramparo T, Pierce K, Lombardo MV, Carter Barnes C, Marinero S, Ahrens-Barbeau C, Murray SS, Lopez L, Xu R, & Courchesne E (2015). Prediction of Autism by Translation and Immune/Inflammation Coexpressed Genes in Toddlers From Pediatric Community Practices. JAMA psychiatry PMID: 25739104