CHRM4 and major depressive disorder: SBI patients who reported depression had significantly lower median titers of anti-AT1R (10 vs. 16, p < 0.001), anti-β1AR (8 vs. 23, p < 0.001), anti-β2AR (5.1 vs. 6.9, p = 0.04), anti-ETAR (7.7 vs. 11.3, p < 0.001), anti-M1R (2.13 vs. 3.04, p = 0.008), anti-M2R (3 vs. 5, p < 0.001), anti-M3R (5.9 vs. 7.9, p = 0.011) and anti-M4R (5 vs. 9, p < 0.001) in comparison to healthy controls without SBIs.