The main belief of the neurodiversity movement is that autism is a naturally occurring genetic variation. The differences in the brains of autistic persons versus those of "neurotypicals" are no more significant than differences between blondes and brunettes. A common belief is that numerous genes in small amounts accrue certain evolutionary benefits but in large amounts cause autism. According to Simon Baron-Cohen and Temple Grandin the reason autism has stayed in the population despite the fact that autistic people usually don't have children is that it has traits that are adaptive and have evolutionary value. For example attention to detail as measured by the embedded figures test, high scores on the block design test and pattern recognition. Grandin has gone so far as to say that we'd all be cavemen if it weren't for autism genes.
New research from the Cold Spring Harbor Laboratory in New York would seem to refute that contention. The scientists found that a number of cases of autism to be caused by rare genetic mutations in vulnerable genes. These mutations were spontaneous, and due to the fact that autistics rarely reproduce these mutations don't stay in the population. In some cases, they were transmitted by the mother who was less vulnerable to the mutation and did not become autistic. Here is the study in its entirety in case anyone is interested in reading it. I read it, albeit with limited understanding, not being a scientist.
The scientists used a databank from the Simons Foundation that included multiple families with one autistic child. Of course, one limitation is that they did not study multiplex families in which more than one child has autism. This is not an uncommon occurrence as siblings of autistic children are far more likely to have autism than a child in the general population. With fraternal twins it is more likely than in siblings. In identical twins there is an even higher concordance rate, though not 100%. Gadfly wonders if different results would be found for families with more than one autistic offspring. Is it possible they have different genetic mutations or environmental causes for their autism?
Even though my father is a retired engineer and the prevalence of autism among children of engineers and physicists may be higher than in the general population, this makes some sense in my case as there is a history of mental illness, depression, ADHD, learning disabilities and probable autism in my mother's side of the family. It's possible my mother carried some sort of genes that did not affect her because being a female provided some order of protection and they were passed down to me. My non-autistic sister may have been afforded the same protection by virtue of her femaleness.
Another point of contention is how much of this is 100% genetic or just a predisposition with environmental causes? The fact that fraternal twins are no different genetically than regular siblings, yet have higher concordance rates suggests a environmental factor. Likewise with identical twins who are nearly the same genetically yet don't have a 100% concordance rate.
This would seem to refute the contentions of the neurodiversity movement that autism is the result of naturally occurring random genetic mutations that have evolutionary benefit and thus have stayed in the population. Of course, I might be going wrong somewhere due to my lack of scientific knowledge and training.
It would also refute the contentions of the anti-vaxers or others who believe something else in the environment, such as pesticides and ultrasounds have caused a widespread autism epidemic and that genetics plays a limited role if any at all. They say there is no such thing as a genetic epidemic. That the prevalence would not have gone from 1 in 2500 to 1 in 68 just due to some de novo genetic mutations. The explanations of some that I have read is that this study was financed somehow by big pharmacy who wants to cover up the fact that they somehow caused the autism epidemic.
I suppose the neurodiversity movement also has an explanation for what is wrong with this study and why the common genetic variation is correct and the limited number of genes that are vulnerable to de novo mutations that disappear from the gene pool have nothing to do with it. I await their explanation.