SIGIRR and major depressive disorder: Between TNF-α secreting cells of 10 MDD patients (1 male and 9 females) and 10 controls (2 males and 8 females), mRNA levels of SIGIRR and TNFAIP3 were significantly different, using Mann-Whitney U Test (p = 0.023 and 3.2 × 10−4, respectively).