To our knowledge, this is the first report of a genome-wide significant association for anorexia nervosa. As is typical of many GWAS loci for complex disorders, the region implicated is broad, with a modest odds ratio of 1.2 but at a common allele (MAFcontrols=0.44) (25). Our genome-wide hSNP2 estimate of 20% for anorexia nervosa supports a substantial role for common genetic variation. As we now expect (26), the hSNP2 estimate reported here indicates that common variants account for a sizeable portion of twin-based heritability ( hTwin2 48–74%)6. Further, these results fit with the expectation that hTwin2 should exceed hSNP2, because the former captures the effects of all types of genetic variation (common and rare, as well as variation not captured with current methods).
