Well over a hundred studies have been published that assessed whether measured genetic variants are associated with candidate endophenotypes. Of these, only a dozen, summarized in Table 6, meet our admittedly liberal criteria. Despite representing research that is commendable in certain respects, the studies in Table 6 illustrate some of the reasons that candidate gene studies are so fallible, as we discussed in section 7.1. Although 12 studies are listed in the table, nine of them were contributed by three research groups. The studies reported within each group involve overlapping or identical samples, and thus should not be considered independent reports despite the fact that they examine different candidate genes or candidate endophenotypes. These overlapping reports also do not conduct project wide correction for multiple testing, so they do not adequately adjust for Type I error, a problem that is now well recognized in molecular genetic research of complex traits. Although the table indicates effects that were nominally significant by the criteria used (p < .05 or p < .01), none reach significance if all variants within all genes reported
