More and more evidence is surfacing that environmental factors may be at play in the rising rates of autism, which the CDC estimates affects 1 in 88 children. A new study has found yet another interplay between our genes and environmental toxins as suspect for the increasing risk of autism.
Looking at more than 400 children between the ages of 2 and 5, researchers also considered genetics and air-pollution exposure factors like local traffic-related pollution, how close mothers and children have lived to busy roadways, and regional air-quality reports.
They found that the MET gene variant, which is very common in the general population, is even more prevalent in individuals with autism. About 60 percent of children with autism have this genetic risk variant. “It’s not a gene mutation; instead, it is a genetic risk variant that is associated with autism.”
Children with that gene variant who also experienced high air-pollution levels were even more likely to be diagnosed with autism spectrum disorder. The types of air pollution that seemed most likely to trigger autism in susceptible children include air pollution particles less than 10 microns in diameter and nitrogen dioxide, both of which increase the risk of autism threefold in kids with the risk genetic variant.
Earlier this year, we reported on a Harvard study that found a similar connection between autism and in utero exposure to air pollution:
According to the first national study on in utero air pollution exposure and autism rates conducted at the Harvard School of Public Health (HSPH), as reported by Time Healthland:
They compared autism rates with levels of pollutants measured by the U.S. Environmental Protection Agency during the womens’ pregnancies. Expectant mothers who lived in the 20% of locations around the country with the highest pollution levels in the form of diesel particulates or mercury were two times as likely to have a child with autism compared with those who lived in the 20% of locations with the lowest levels of pollution. Women who lived in the 20% of areas with the highest levels of other pollutants, like lead, manganese, methylene chloride and other metals, were nearly 50% more likely to have a child with autism.
The Harvard study did not link the air pollution’s influence on a specific gene variant as the USC study did, as far as I can tell.
USC News explains:
“Our research shows that children with both the risk genotype and exposure to high air pollutant levels were at increased risk of autism spectrum disorder, compared to those without the risk genotype and lower air pollution exposure,” said the study’s first author, Heather Volk, assistant professor of research in preventive medicine and pediatrics at the Keck School and principal investigator at The Saban Research Institute of Children’s Hospital Los Angeles…
“Although gene-environment interactions are widely believed to contribute to autism risk, this is the first demonstration of a specific interaction between a well-established genetic risk factor and an environmental factor that independently contribute to autism risk,” said Daniel Campbell, assistant professor of psychiatry and the behavioral sciences at the Keck School and the study’s senior author.
“The MET gene variant has been associated with autism in multiple studies, controls expression of MET protein in both the brain and the immune system, and predicts altered brain structure and function,” he added. “It will be important to replicate this finding and to determine the mechanisms by which these genetic and environmental factors interact to increase the risk for autism.”
Replication of the study is important, and it would make sense that cities with the most air pollution would have the highest autism rates, yet that may not ring true given the genetic factor.
The study of epigenetics is growing, and I feel it will explain many diseases growing prevalence in the near future. We cannot underestimate the interplay between our genetic make up and our environment, both positive and negative as the source for health and well-being.
Air pollution is a crisis on our planet. Recently, Shanghai has experienced unbelievable air quality problems, and the EPA has had to defend regulations on mercury and air toxins standards for power plants in court because of the cost to the industry. What about the cost to human health?