SEP 03, 2017 05:46 PM PDT

Uncovering Genetic Mutations Impacting Autism Risk

WRITTEN BY: Carmen Leitch

OOPS! THAT EXPERIMENT FAILED...

It's not your fault! Something went wrong with our formula.
Please begin your experiment again by clicking here.

If this error continues to occur please contact us at support@labroots.com.

Around one in every 68 children in the United States is affected by autism spectrum disorder. The etiology of the disease is not understood, and many different theories have been put forth. Evidence of genetic risk factors is growing. A new study assessed 2,300 families that had a child with autism, looking for genetic causes. This work was focused on finding mutations that don’t happen throughout the entire genome, and as such might have been missed by other studies.

Some mutations now linked to autism risk occur after the zygotic stage of an embryo (human embryo at 8-9 weeks shown) / Credit:Wikimedia Commons/ Anatomist90

These kinds of mutations, postzygotic mosaic mutations (PMMs), happen after a zygote has formed during development. This results in a mix or mosaic of genetic information, some of which has a small change. The degree of mosaicism depends on when the mutation happens during development, and where it occurs in the genome. PMMs have been associated with some neurological disorders, and investigators wanted to look for them as a potential contributor to autism.

By using new tools in next-generation sequencing, the researchers found evidence that around 22 percent of mutations that have been reported before were actually happening during development, and not at the time of conception as was thought.

"This initial finding told us that, generally, these mosaic mutations are much more common than previously believed. We thought this might be the tip of a genetic iceberg waiting to be explored," explained the principal investigator of the work, Brian O'Roak, Ph.D., an Assistant Professor of Molecular and Medical Genetics in the OHSU School of Medicine.

Because these samples were from families, the investigators were able to assess how PMM rates were impacting affected and unaffected siblings. The team discovered that “silent” mosaic mutations, which are thought to have no effect on proteins, were happening at higher levels in affected sibs. This mosaicism was increasing risk for around two percent of people with autism in the study group.

This work found evidence that mosaic mutations that affect developmental genes, or genes that are resistant to mutation, happen more often in individuals with autism. The risk these mutations contribute is small though; estimated to be around one or two percent. However, many of the PMMs happened in genes that have been previously associated with autism, increasing the risk to three or four percent.

After tracing some of these mosaic mutations to parents, there was evidence that some were indeed carried by parents, indicating that they could exert an effect early in development. In any event, more research in this area looks like a promising place to look for autism risk factors.

"In addition to a need for broader research focused on the role that mosaicism plays in autism and related disorders, our data argue that physicians should be requiring more sensitive testing of both children and parents when a new disorder-related genetic mutation is identified," said O'Roak. "These mutations can go from being in a few percent of the cells of a parent to 100 percent of the cells of a child. If present, at even low levels in the parents, the risk of additional children receiving this mutation is dramatically increased."

For more on how genes relate to autism, check out the video above from University of California television.

Sources: AAAS/Eurekalert! Via OHSU, The American Journal of Human Genetics

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
JUN 11, 2018
Microbiology
JUN 11, 2018
Seeing Gene Transfer as it Happens
Microbes can pick up new pieces of genetic material; now it's been captured in action for the first time....
JUN 26, 2018
Cell & Molecular Biology
JUN 26, 2018
Growing Closer to 3D Printed Organs
One company is using 3D printing to build human tissues; they've now made a structure with functional capillaries....
JUL 09, 2018
Cell & Molecular Biology
JUL 09, 2018
Scientists Found a New Way to Treat Lung Cancer
Small cell lung cancer is an aggressive type that can be fatal; there were few treatments for the disease. That may have changed....
JUL 10, 2018
Cell & Molecular Biology
JUL 10, 2018
Newly Found Enzyme can Help Turn Plant Waste to Plastic
Scientists discovered an enzyme that can harvest a versatile molecule from trash....
AUG 01, 2018
Cell & Molecular Biology
AUG 01, 2018
Levels of One Molecule, LAC, can Diagnose Depression
Depression can be hard to classify and therefore, challenging to treat. New work could help change that....
AUG 11, 2018
Videos
AUG 11, 2018
Hit The Sweet Spot - MIT's Image Awards
MIT researchers are trying to engineer a smarter insulin....
Loading Comments...