There is no single "autism gene", nor does there seem to be a single copy error that can be said to be the cause (not like, say, trisomy 21 leading to Downs Syndrome). Instead, there seem to be a lot of single-gene copy errors that can contribute; further, some possible epigenetic causes have been identified (for instance, is the higher rate of autism in areas of greater air pollution due to the effects of air pollution on developing fetuses, or is it an artifact of the fact that said areas also tend toward higher-tech employment, which tends to attract people on the spectrum, or could it be some combination of these, or even just a statistical fluke?).
If you'd like to start a career in genetics with a specialty of isolating autism causes, this would seem to be a field with lots of job security...
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Sodium is a metal that reacts explosively when exposed to water. Chlorine is a gas that'll kill you dead in moments. Together they make my fries taste good.