A study by Wong et al (2008) found that two untranslated regions SNPs critical for antigen processing and T-cell differentiation in proteasome b4 subunit (PSMD4; rs2296840) and in T bet (TBX2; rs17244587), T and A, respectively, were significantly associated with MDD (Wong et al, 2008). This evidence concerns the gene TBX2 and major depressive disorder.