P2RX7 and depressive symptom measurement: The majority of studies investigating the role of P2RX7 in depression have focused on rs2230912, but more recently it has been suggested that tagging all variations could help determine the extent of the role P2RX7 plays in mood disorders [23], and understanding the role of other variations may shed further light on the association between P2RX7 and disease susceptibility/protection [41].