It is possible that this disease is a combination of biochemical and environmental factors. Those susceptible may require particular circumstances to activate the disorder.
Babies need breast feeding.
I think this might provide a clue into particular circumstances that activate the disorder.
Mercury, Autism and the Global Vaccine Agenda - Google Video
David Ayoub, M.D. goes through the relations of Mercury to Autism
http://video.google.com/videoplay?docid=6890106663412840646&q=vaccines+autism
Early Downward Trends in
Neurodevelopmental Disorders Following Removal
of Thimerosal-Containing Vaccines
http://www.jpands.org/vol11no1/geier.pdf