There was a significant association between BDNF rs6265 and TRD, with a higher percentage of patients with CT genotype in the TRD group, compared with the non-TRD group, which represents a three-fold higher risk of TRD development for patients carrying CT genotype (OR: 3.2; 95% CI: (0.975–10.501); p = 0.049). Here, BDNF is linked to treatment resistant depression.