In a separate 5-factor regression model using the clinical HRSD for depression severity, severity was associated with increased expression of P2RX1 (adjusted t = 2.44, p = 0.026) and P2RY1 (adjusted t = 2.10, p = 0.051), but not TRPV4 (adjusted t = −0.14, p = 0.893) or IL10 (adjusted t = −0.35, p = 0.734). This evidence concerns the gene P2RX1 and major depressive disorder.