On May 4th, Dr. Janine LaSalle from UC Davis and (the soon to be Dr.) Keith Dunaway presented on recent research investigating the role of environmental factors in individuals with Dup15 Syndrome. Individuals with a mutation on chromosome 15 are often diagnosed with autism and previously it had been assumed that these individuals were destined to have a diagnosis due to their genetics. Dr. LaSalle shows that many of the genes in a critical region of chromosome 15 are tied to turning genes on and off via a process called methylation. Environmental chemicals or other exposures may also work on these genes to turn on or off gene expression epigenetically. The first half of the webinar reviews crucial ideas in gene x environment interactions and epigenetics, the second half describes experiments using brain tissue of those with Dup15 Syndrome and autism, as well as cell lines, to understand the role of PCBs in gene expression.
Last month, UC Davis researcher Cyndi Schumann used resources for the Autism BrainNet to look at what causes differences in the rates of diagnosis between males and females. Consistent with other studies on this topic, males and females don’t show differences in the rates of autism genes, but rather in the way that the brain controls other genes that code for things like neuroinflammation and development. Clearly more studies are necessary but it is consistent with the Female Protective Effect in autism. The full text can be found here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5294827/
And also, there was a study on genital herpes and autism that CNN got totally wrong.
With hundreds of genes, thousands of environmental factors, and now sex being variables in determining risk for autism, where should science start? Over the decades researchers have been able to start narrowing down the combinations based on specific behaviors of interest, genes, and mechanisms which may narrow down which gene, which environmental factor and which sex. Dr. Sara Schaafsma and Dr. Donald Pfaff from Rockefeller University combined the three, and found that epigenetic changes in an autism risk gene called contact in associated protein like 2 contributed to elevation of risk for autism behaviors following maternal infection. In other words, being male and having the mutation produced small changes, increased by the environmental factor. In another separate study, Dr. Keith Dunaway and Dr. Janine LaSalle at UC Davis used brain tissue to look at a rare variant for autism on chromosome 15. Typically, mutations of this area of the genome are thought to cause autism. However, the effects of these mutations are also increased when environmental factors are present, leading to more de novo mutations. These are all examples of scientific breakthroughs that are helping better understand what causes autism. Even when it looks like one thing, it’s multiple things.