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Study Links Epigenetic Changes in Mom’s DNA to Babies’ Autism Symptoms

Changes may reflect environmental exposures and other factors that increase autism risk
May 14, 2015

Researchers studying families at high risk for autism have linked epigenetic changes on the DNA of pregnant mothers to the severity of their children’s autism symptoms at 12 months.

Epigenetic molecules regulate when genes turn on and off. Their tight control of gene activity is particularly crucial during early brain development. Age and exposure to environmental toxins are among the factors known to alter epigenetic regulation. Genes also play a role.

The newly reported findings add to a growing body of research that implicates epigenetic changes in the development of autism.

“Our results, though preliminary, are consistent with the idea that a mother’s experiences may influence the severity of autism symptoms in her child,” says study co-author Daniele Fallin, director of the Wendy Klag Center for Autism and Developmental Disabilities, at Johns Hopkins University.

Dr. Fallin and colleagues presented their study’s preliminary results today at the International Meeting for Autism Research (IMFAR), in Salt Lake City. A number of Autism Speaks research grants help support their ongoing research.

In 2012, Autism Speaks awarded Dr. Fallin its first Geier Autism Research Grant in Environmental Sciences to advance her pioneering work on the gene-environment interactions involved in autism epigenetics. 

Tracking babies at high risk for autism
The 77 mothers and 77 children in the study are part of the larger Early Autism Risk Longitudinal Investigation (EARLI).

In 2008, EARLI researchers began following pregnancies and babies in families already affected by autism. Because autism tends to run in families, autism rates are notably higher among the younger siblings of children who have autism. Autism affects around 1 in 5 “baby sibs.” By comparison, autism’s prevalence in the general population now stands at 1 in 68.

Using blood samples from the pregnant women, the researchers analyzed epigenetic patterns across the whole genome (the entire length of each woman’s DNA). Specifically they looked at the epigenetic mechanism of methylation. In essence, a methylated gene is a gene in the “off” position. An unmethylated gene is turned on and active. (See DNA illustration at top.)

The researchers then assessed the women’s babies for autism symptoms at 12 months using the standardized Autism Observational Scale for Infants. Their analysis associated several distinct DNA methylation patterns with significantly higher levels of autism symptoms in the 1 year olds.

Epigenetic changes may reflect environmental exposures
“If these findings are confirmed,” Dr. Fallin says, “the next step is to explore how these epigenetic differences may relate to a mother’s age, environmental experiences and genetic predispositions. Above all, perhaps, these findings highlight that we need to be looking at moms as well as babies when we look for autism’s prenatal risk factors.”

Conversely, Dr. Fallin says, such epigenetic changes may ultimately serve as tell-tale markers for past environmental exposures. For instance, further research might identify epigenetic markers that reflect a past exposure to, say, high levels of air pollution. 

“If we could do a better job of measuring how particular environmental exposures predispose to autism – in this case with epigenetic signatures of specific exposures – this might help guide public policies and health recommendations to reduce autism risk,” Dr. Fallin explains. “Greater understanding of these mechanisms might also lead to better interventions – pharmaceutical or behavioral – for preventing or treating autism.”

Comments developmental pediatrician Paul Wang, Autism Speaks Head of Medical Research Research:
“As a relatively new field of investigation, epigenetics has taken us beyond traditional genetics to show that not only are genes and gene mutations important, we also need to look at where and when genes are turned on or turned off – in this case through the epigenetic mechanism of methylation. Since methylation is affected by the environment, these findings provide more evidence that environmental exposures that affect the mother can be important in understanding the causes of autism. However complex the issues, we need to keep working to better understand these exposures and how they affect the developing brain.”

Read the scientific abstract of the results presented at IMFAR here.

Autism Speaks continues to support EARLI and its related investigations into environmental risk factors for autism with a number of research grants. To learn about participating in EARLI, visit http://www.earlistudy.org.

For more on research involving high-risk families, also see “Research by Autism Speaks Baby Siblings Research Consortium.”

Autism Speaks is a major sponsor of IMFAR. For more daily news coverage, click here.