Even better, address metabolic pathway problems (as revealed by genetics) and the problem goes away for most people with autism,...although probably not all.  

I'm shocked that scientists are lured into looking for symptoms (the lack of protein), rather than the cause, the metabolic basis of the disease in most people, which likely causes problems with the protein because of faulty metabolism.    

How do we know fixing metabolic problems works?   Parents (mostly in the US) of children who are autistic who have treated their children (with guidance from specialists in functional medicine as well as knowledge of their folate metabolism and other key metabolic marker genetics) and so the condition has reversed itself once the impaired metabolism was addressed.

Guess why this doesn't make the MSM?   There's very little money in it compared with expensive therapies, treatments, drugs, and so on.   

The reality is that civilization won't win a toxicity arms race.   Nature will.