CHRM4 and major depressive disorder: No significant differences were detected in the median titers of anti-β2AR (p = 0.88), anti-M1R (p = 0.72), anti-M2R (p = 0.48), anti-M3R (p = 0.52), anti-M4R (p = 0.56) and anti-M5R (p = 0.16) autoantibodies between healthy controls without SBIs and subjects with SBIs who did not report depression (Figure 4 and Table 4).