Epigentics is a relatively new field of study involving the changes in genetic expression (versus gene sequence). This ability to turn on and off genes is a way for humans to rapidly adapt to changes in our environment. Nutrition and toxins can influence these changes in gene expression. This gene expression can be affected during adulthood or in utero, and can be caused by nutrient deficiencies (and reversed by good nutrition) and by toxins.
These epigenetic changes are influenced by DNA methylation. You may have heard of DNA methylation, and methylation in general, in relation to autism. Jill James PhD has done a number of studies on B12 and folate deficiency (two nutrients essential in the methylation cycle that lead to glutathione production) and glutathione status in children with autism. She found that many children lacked proper methylation (and transulfuration) and adequate glutathione levels.
Glutathione acts as a potent antioxidant and detoxifier, and it helps support proper immune function and inflammation.
A recent study published in Environmental Health Perspectives uncovered how pollution in the air caused changes in genes associated with glutathione. This research studied older men (not with autism) and found that the chemicals from burning coal and wood, black carbon and sulfate respectively, caused gene changes associated with glutathione pathways.
This study is very relevant to autism as it shows how specific toxins affect gene expression, and particularly glutathione status. This is an exciting study that provides further support that autism is a combination of genetic predisposition and environmental assault.
Madrigano J, Baccarelli A, Mittleman MA, Wright RO, Sparrow D, Vokonas PS, et al. 2011. Prolonged Exposure to Particulate Pollution, Genes Associated With Glutathione Pathways, and DNA Methylation in a Cohort of Older Men. Environ Health Perspect doi:10.1289/ehp.1002773