Decent article. I remember reading a previous article about the potential increase in autism rates amongst Somali immigrants in Minnesota. One of the immigrant women if I remember correctly had been quoted as saying (paraphrased) "we wouldn't have a problem with Autism in Somalia because we'd just force the kid to go out into the street packed ass-to-elbow with bazillions of other kids and that would normal them up right quick!" Ultimately that's not much different than a lot of the quackery we've seen here in the US surrounding autism, like the early "refrigerator mothers" theory, before we realized how ridiculous that was. But it does speak to this notion of not really knowing what the rates of autism are in Somalia before they emigrate to wherever.

I think further research into the effect of vitamin D during pregnancy might be interesting, although I doubt that it will show much in the way of a causal link between D deficiency and autism.

In this article they say that light-skinned people like us produce vitamin D much faster during sun exposure, meaning that we require much less sun exposure in order to get a really good dose of D. Then add to that the fact that simple observation has borne out a number of common "risk factor" relationships with autism - the propensity of similar characteristics in other family members, a history of systemizing jobs in the family (engineering, math, etc). Of course, there are people who have claimed that various things have helped their children over the years and some of them stand up to scientific scrutiny and others don't. The observation of engineers in the family thus far has borne itself out under rigorous study, while we're still waiting for the results of the first study of the GFCF diet (as far as I know).

But these things had to be observed casually before someone put money into studying them as potential causes of autism... and that to me begs the question, if it takes very little sun exposure for a light-skinned mother to get a good healthy dose of vitamin D, then how come nobody seems to have made any casual observation that all these light-skinned mothers of autistic children seemed awfully shut-in, if not permanently at least during their pregnancy? I would think with light-skinned women in particular, there would have been some casual observation of say a strong relationship between agoraphobic mothers and autistic children... but I've never even heard of a single agoraphobic mother. Granted I don't know what the rate of agoraphobia in the general public is either, so my knowledge isn't airtight there.

Taking it just a little bit further, then I'd want to start looking at twins as well... because the vitamin D deficiency that's really important is during the mother's pregnancy, I would think that would have to affect twins in some particular way. Specifically I would think that the likelihood of both twins being autistic would be constant between both identical and fraternal twins. Since they both had the same mother through the same pregnancy and she got a constant x amount of vitamin D during that pregnancy for both children, you'd think that whether they were from the same egg or not wouldn't have much effect on their becoming autistic if vitamin D deficiency is a significant factor. But having read (not much) about autism among twins, I don't think that's what the studies showed. I think they showed that the likelihood of autism in both children was statistically significantly higher if they were identical twins from the same egg.

Maybe it's a contributing factor... right now I'm just not placing it high in my list of probabilities. I could be wrong.