spicemonster - I;m just back from a very very interesting conference. Something that struck me was a talk where they divided autism into 2 main groups (although there would be lots of subgroups with those). One group had autism caused by many genes- if you looked at the families there was either autism/AS or traits in the family tree repeatedly.This matches something I've noticed for years in lots of families where kids have AS/HFA.
The other group seemed to be matched to one gene (although different individual genes). There was no family history of autism or traits - and in that case they seemed to say (iirc) that it was more likely to be a single gene that could then be affected by a trigger.
Of course big oversimplification.
I also went to a number of the talks on immunology and there were some mentions of having a susceptible gene (as mentioned above) then something like a maternal infection when pregnant- which would affect the developing foetus' immune system. A later trigger (and 'the dreaded vaccines' were mentioned as one potential trigger) and you're merrily on the road to autism.
Again a mass oversimplification - and probably partially remembered. But interesting.
There was quite a bit of follow on from this research on the immune system in autism at the conference.
IN ds1's case he had some weird things happen right before his regression. First a mole he had went very crinkly for a number of months. It was enough for us to see a dermatologist who wasn't sure what it was, but said it had become more keratinised. It then swelled up and started leaking a white fluid, then ds1 became covered head to foot in blisters. This all became very nasty and infected. Swabs were inconclusive but it was diagnosed by a specialist as eczema herpeticum (when eczema becomes infected by the herpes virus) and was treated aggressively as this can be fatal. Then he regressed. His paediatrician did say this was likely to be the trigger for his regression - so I find it odd that a viral infection that is naturally caught can be so easily accepted as the trigger, whilst one that is artificially introduced can be deemed to never be involved. I do think the numbers of post MMR regression are small, but the people I've spoken to who link it have very clear stories, which are different from others. And having observed a regression myself (which has been accepted as such) I don't think it's that difficult to spot. One of the mum's I've spoken to had a child who regressed when they were almost 4 anyway and it's hard to miss that!