Monday, November 05, 2007

Regions of rapidly evolving genes: evidence of genetic control of the rate of adaptation and disorders of evolution

About four weeks ago I wrote about the possibility that "autism" and "schizophrenia" might be "disorders of evolution". If the genes that code for brain function are experiencing very high variation levels, and thus rapid adaptation and differentiation (evolution), it's plausible that we'd see a range of disorders related to maladaptive variations.

Back then I thought the post was a bit daring, the sort of thing that might cause some in my vast readership to think I was being a bit eccentric.

Nowadays though, that post seems pretty mainstream:

Mouse study finds hotspots of genome instability (John Timmer)

[Nature 10/28/07] ... The data suggest that certain parts of the genomes are "hotspots" that both undergo change frequently, and produce changes that are well-tolerated by the organism. These hotspots undergo changes up to 10,000 times more frequently than quiet areas of the genome, and can undergo multiple, successive changes. The fact that the organism appears to tolerate these changes isn't due to an absence of genes in the CNVs. In the 18 mentioned above, there were a total of 43 genes, including some involved with reproduction, immunity, and brain function.

There's been an idea floating around for a while that suggests that genomes evolve to the point where they work well with evolution. A genome that, by chance, winds up with genes that are sensitive to dose effects in a region that's stable is more likely to be be inherited. In the opposite case, where different doses of a gene might help an organism adapt to different environments, having that gene located in an unstable area might be selected for. The new data doesn't directly address this proposal. But it does find that there unstable areas of the genome that are likely to undergo major changes within the span of less than 100 years, which seems to be a prerequisite for the proposal to be taken seriously.

It turns out Timmer has at least one other post relating these types of gene rearrangements to autism.

I'm ready to be that within six years medical students will consider a wide variety of neuropsychiatric disorders to be "disorders of evolution". You'll have a jump on those whippersnappers ...

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