data are incompatible with the hypotheses recently advanced elsewhere that there is only a single schizophrenia risk gene or indeed that all risk is epigenetic26. The existence of multiple genes of small effect suggests that the collection and application of larger samples should deliver many more associations, with the caveat that casting widely for such samples is done in such a way as to avoid the negating effect on power of increasing the (as yet unknown) degree of genetic heterogeneity within diagnostic categories27.
