Finally, a recent GWAS identified FRMD4A associated with substance dependence (Johnson et al. 2008). It is interesting that our result is consistent with that of Johnson et al., as we focused on ND, whereas Johnson et al. focused on substance dependence phenotypes assessed by DSM and FTND. However, Johnson et al. did not report any replication result. As far as we know, the present study is the first GWAS to show that FRMD4A is directly associated with ND with an independent replication.
