By Robert Glatter, M.D.
May 13, 2015
"...“preliminary findings show DNA methylation – tags on DNA that control when and where in the body particular genes are turned on – in mom’s blood during pregnancy may be associated with how the baby later performs on autism-related assessments at age 12 months.”
The interrelationships and interaction of environment, genes, and parental age have all been linked to autism spectrum disorders (ASD).
Epigenetic marks–molecular tags on DNA that tell genes when to “turn on” or off—are also influenced by the interplay of genes, environment and parental age.
Maternal DNA methylation represents such a common tag, and as a result, the study of DNA methylation may provide important clues and perspectives into autism development.
Based on current thinking and research directions, prenatal development is considered the most important time period for autism risk and onset. Epidemiologists consider this a critical time to evaluate changes in DNA and thus may provide a snapshot into the factors that shape the development of autism in infants.
Research by M.D. Fallin of the Johns Hopkins University School of Medicine and additional colleagues, sought out to determine whether DNA methylation in mothers during pregnancy was associated with childrens’ autism symptoms at one year, based on their performance on the Autism Observation Scale in Infants (AOSI).
The researchers analyzed blood samples from 79 mothers who participated in the Early Autism Risk Longitudinal Investigation (EARLI), a pregnancy study of families at high risk for autism, because they have already had given birth to autistic children.
Fallin and his colleagues found specific DNA tags in maternal blood that were linked to the baby’s AOSI score at 12 months.
It was noted in this study that the set of DNA tags most often linked to AOSI also overlapped with genes previously implicated in development or ASD. Nordahl’s group also recently noted associations between AOSI score and father’s sperm DNA tags–which can be influenced by environmental exposures, age, or inherited genes.
Taken together, these maternal, paternal and child findings may give further insight about the role of epigenetic influences on ASD risk.
Margaret Fallin, Ph.D., Professor and Chair, Department of Mental Health, at the Johns Hopkins School of Medicine and colleagues will present findings of their research, Maternal Blood DNA Methylation during Pregnancy and Autism Observational Scale for Infants (AOSI) Score at 12-Months in the Early Autism Risk Longitudinal Investigation (EARLI) at the 2015 International Meeting for Autism Research (IMFAR), May 13-16 in Salt Lake City.
Fallin explained that “preliminary findings show DNA methylation – tags on DNA that control when and where in the body particular genes are turned on – in mom’s blood during pregnancy may be associated with how the baby later performs on autism-related assessments at age 12 months.”
Fallin explained that their results will have to be studied in other groups in order to replicate findings seen in their research. If such results can be reproduced, it may suggest that epigenetics can offer insights into autism risk. Fallin also adds that that “it is important to consider biological samples from parents around the time of birth as well as from the baby who may be affected.”
Fallin emphasized that his group’s findings on their own will not change how patients with autism are ultimately diagnosed and managed at this point in time. As Fallin explained, “the consideration of epigenetics, and of parental biosamples around the time of birth, may shift research focus on the causes of autism in a way that could ultimately inform the biological understanding of autism and thus inform new prevention and treatment approaches.”
Fallin believes that his findings are quite preliminary, but, “in combination with results from our group and others, point to the potential importance of epigenetic marks in understanding autism risk and to the need to examine parental biological samples near the time of birth. This highlights the need for more studies with longitudinal birth cohort designs like the EARLI study.”
“Epigenetic regulation of gene expression has long been thought to play a role in autism etiology but clear links to disease biology have largely been missing, said Mathew Pletcher, Ph.D., Vice President, Head of Genomic Discovery at Autism Speaks. “This study provides additional support for the idea that epigenetic mechanisms are disrupted in autism. At the same time, the study also underscores the difficulty in translating this type of data into clear biologic understandings.”
Pletcher explains that additional work will need to be done in order to appreciate if the changes in methylation noted in this investigation may impact normal neurological development.”
“Scientists agree that the risk factors for autism are likely both genetic and environmental, however, the mechanism by which the two interact together has not been studied enough,” explained Alycia Halladay, Ph.D., Chief Science Officer, Autism Science Foundation.
“Epigenetics, sometimes called the “ghost in our genes” is the way that environmental factors turn on or turn off gene expression, without making changes in the DNA sequence. Methyl groups attach to specific parts of the DNA to turn on or turn off DNA expression, which can affect the way the brain forms, develops and functions. This mechanism has shown to be instrumental in how genes and the environment contribute to cancer, obesity and schizophrenia.”
“Dr. Fallin’s group has been able to identify specific epigenetic marks in mothers during pregnancy whose child goes on to show symptoms of autism. These findings should not be interpreted as a surrogate diagnostic test, but rather provides additional scientific evidence that the biological features of autism are seen during prenatal time windows; and shows that genetic and environmental factors, working together rather than each in isolation, affect autism risk.”
Halladay went on to explain that the research being conducted in Dr. Fallin’s lab is part of a larger effort that involves biospecimens from mothers, fathers, and children with ASD and converges with data from postmortem brain tissue.
“While different, they all are converging on the idea that epigenetic mechanisms contribute to risk of autism. In order to turn these findings into potential preventative measures, there needs to be more research on which environmental factors target epigenetic mechanisms on genes associated with ASD,” added Halladay.