For example, Xie et al[28] found that the number of purinergic 2 X 7 (P2X7) receptors expressed on peripheral blood mononuclear cells in pSS patients were significantly higher than that of the controls, suggesting that in pSS patients P2X7 receptors may contribute to anxiety, depression, or both. The gene discussed is P2RX7; the disease is depressive disorder.