After adjusting for those conventional depression risk factors such as age, gender, the AA (of the A-1438G polymorphisms of the 5-HT2A gene), Val/Val (of the Val66Met polymorphisms of the BDNF gene), CC (of the C-1019G polymorphisms of the 5-HT1A gene) genotype still had an approximately. Here, BDNF is linked to major depressive disorder.