In support of the preceding observation, the BDNF genotype × number of reported CAs interaction analysis showed a protective effect of the Met allele on the risk for MDD (Wald's 6.5, OR 0.2; CI 0.09–0.7; P < 0.02); this effect was only evident in females (Table 3). The gene discussed is BDNF; the disease is major depressive disorder.