On the one hand, a meta-analysis of 12 studies of VNTR of the DRD4 gene polymorphism with depression performed by López León et al. (2005) revealed that the short allele 2 is associated with depression [22], but on the other hand, Gafarov et al. [23] found that male carriers of the 4R/6R genotype of the DRD4 gene were more likely to be found amongst subjects with a severe level of anxiety and depression and the carriers of the DRD4 allele 6R were more common among males diagnosed with depression. Here, DRD4 is linked to major depressive disorder.