In response to my comments, Juan Carlos Lopez had this reply on Spoonful of Medicine:

Candidate genes? We already have many more candidate genes than we know what to do with. I’d argue that candidate genes are, in fact, part of the “genetic noise” Debra refers to.

What this field needs is, among other things, new animal models that allow us to make more thoughtful experiments on the biological basis of psychiatric disease.

In the absence of good models in which to test the functional relevance of whatever genes the screening process identifies, the massive investment that Apoorva highlighted will bring rather paltry returns.

He makes an excellent point, but I’m sticking to my guns. Groups of genes that are subtly affected (not wiped out entirely) would not have been found in the small populations studied thus far. Furthermore, the absence of good animal models underscores the need for more information on variation in the only disease model we have: the human.