"We Need To Learn Where Toxins Impact Gene Expression to Find the Cause of Autism."
Posted Mar 04 2009 12:00am
By David Kirby
A new study written up in Science Daily (Mar. 2, 2009) and elsewhere says that researchers at the University of Southern California (USC) and Vanderbilt University have “identified a specific gene variant that links increased genetic risk for autism with gastrointestinal (GI) conditions.”
So far, reporting on the study, to be published in Pediatrics, has suggested that a polymorphism in the Met gene has been identified which, by itself, may explain both brain abnormalities and GI disturbances in children with autism spectrum disorder.
But there may be more to this story than that relatively simple explanation. Is it possible that these genetic variations produce susceptibilities to other environmental triggers, such as toxins? According to one of the lead authors of the paper, Patrick Levitt, PhD, autism cannot be explained by genetic factors alone.
Dr. Levitt made this comment when presenting his findings at the Neuroscience and Nervous System Disorders 2007 workshop on “Autism and the Environment - Challenges and Opportunities for Research,” of the Institute of Medicine.
I hope everyone will look at these excerpts and read the full remarks (both are below) before drawing conclusions about these very significant findings.
STATEMENTS BY DR. LEVITT
1) Environmental factors “must” play a role in ASDs
“Gene–environment interaction is one of the unique properties of the brain. So, of course, regarding ASD, it is not genetic versus environmental, irrespective of whether you think there is a principal cause that is genetic or environmental. Because ASDs have at their core disrupted brain development, in terms of etiology, both genetic and environmental influences must play roles because this is in the basis for brain development.”
2) The Met gene is important for normal nerve and myelin development in the brain:
“It turns out that this gene is expressed in the brain during development and is important for a number of different processes, including cell migration, development of excitatory and inhibitory neurons, synapse formation, and myelination.”
3) The Met gene is also important for proper GI and immune function:
“Met is also involved in gastrointestinal repair, in immune response regulation, and some other peripheral functions that are consistent with the co-occurring medical issues that are described clinically for individuals with ASD.”
4) But manipulation of Met gene expression in animal models can change brain architecture and cause ASD behaviors