Most of the previous studies evaluating the relationship between the Val158Met polymorphism and anxiety and/or mood disorders have been case-control studies. In such studies undiagnosed- and untreated cases with depression and/or anxiety may have been missed. Generalization of the results should therefore be done with caution. Because population-based studies have the potential to intercept undiagnosed- and untreated cases [9], the influence of the Val158Met polymorphism on anxiety and depression should also be evaluated in the general population.
