Autistics: highly evolved
Following on from the two genetic theories of autism I’ve discussed before, and the questioning of the odds involved in new mutations causing autism, here’s a little more news that slipped under the radar recently.
There is a new wrinkle to the genetic research however. Based on family studies, scientists have long characterized autism-linked genes as “heritable.” But recent research shows a surprisingly large number of mutations tied to autism are “de novo” glitches that arise spontaneously in children whose parents don’t carry them.
Such spontaneous mutations have come to light by studying so-called “structural changes” in the genome, which, if DNA’s chemical letters were arranged in book form, would consist of largish mistakes such as duplicated and missing pages. A recent study that got much less attention than the Poling story showed that 7% of kids with autism carry structural changes not found in their parents, compared with less than 1% of such glitches seen in the general population.
“This is really exciting, and a lot of people haven’t picked up on it yet,” says geneticist Stephen Scherer, a co-author of the study at the Hospital for Sick Children in Toronto.
It’s likely that many more such changes will be linked to ASDs as researchers examine a wider array of cases with new gene-scanning tools. Some researchers even theorize that the majority of autism cases stem from such spontaneous mutations.
Why would genes linked to autism be so mutation-prone?
Consider a mutation on chromosome 16 recently tied to autism. The glitch is in a DNA region containing so-called “morpheus” genes, which changed very rapidly as evolution produced ever brainier apes. The genes may well help shape cognitive capacities specific to apes and humans, including ones affected by autism.
Since fast mutation goes hand in hand with fast evolution, it’s likely that the new autism-linked gene lies in a DNA “hotspot” prone to spontaneous mutation. In short, the same phenomenon that helped to rapidly evolve our braininess may contribute to autism. Tracing autism’s roots
So first off – the ‘surprisingly large number’ of de-novo mutations in autistic children has now fallen from ten percent to seven percent (7%) of autistics versus 1% of the general population. The vast majority of autistics aren’t involved in this process.
And second – try as I might, I can’t find any evidence that mutations in Morpheus genes are affected by DNA methylation, transposons, or anything else. This seems to be an effect entirely independent of dietary folate and blah blah blah during pregnancy. In fact, it appears to be an inbuilt evolutionary mechanism for increasing brain power.
It seems that in this case the far-out New Age beliefs that autistics are ‘crystal children’ who are ‘the next stage in our evolution’ are less far-off the mark than WAPF member’s judgemental beliefs that autistics are ‘Pottenger’s children’ whose DNA has been ‘damaged’ by their parents diets.