Further gene-gene interaction analyses showed a significant effect of a two-locus BDNF/GSK3B interaction with MDD (GSK3B rs6782799 and BDNF rs7124442) (corrected P = 0.011), and also for a three-locus interaction (GSK3B rs6782799, BDNF rs6265 and BDNF rs7124442) (corrected P = 0.019).
While BDNF was not associated with major depression as a categorical diagnosis, the BDNF rs7124442 TT genotype was significantly related to worse treatment outcome over 6 wk in major depression (p = 0.01) particularly in anxious depression (p = 0.003) in the German sample.