A new perspective on the genetic basis of brain diseases

An article by Nicholas Wade notes the emergence of a new view on the genetic basis of brain diseases like schizophrenia (see also article by Sands in Nature). There has been a presumption that we looked hard enough, we would find an ensemble of genes whose mutations typically correlated with a disease. The search for common variants in schizophrenia has largely drawn a blank, suggesting that natural selection has done its job in keeping them at bay (after all, reproductive success is compromised in schizophrenics). A view is emerging that the genetic component of the disease may be due to a large number of variants, each of which is very rare (mainly deletions of DNA segments), rather than to a handful of common variants. According to this new idea, schizophrenia continues to appear because it is driven by a spate of new mutations that occur all the time in the population. The new landscape might complicate development of genetic diagnostics for schizophrenia, but not necessarily of therapies based on understanding the underlying mechanisms of the disease.