Regarding particular gene variants, polymorphisms of Glun2a, NR2a subunit of the NMDA receptor, are significantly associated with being an FHP individual, an early onset of risky drinking during adolescence as well as the maximum number of drinks in adulthood, with this association having been replicated in a second large sample.185 A subsequent study also found that a polymorphism in the promoter region of Glun2a is significantly associated with alcohol dependence, with this finding replicated in a second sample.186 A variant of another ionotropic glutamate receptor subunit, Gluk3, was found to be associated with alcohol withdrawal–associated delirium tremens, but not seizures, in a German cohort.187 Another study reported that a polymorphism in Gluk1 is significantly associated with alcohol dependence in Caucasians, although many of the alcohol-dependent, but none of the control, subjects were polysubstance users, which may represent a confound in this study.188
