Specifically, the G allele was associated with a gain-of-function phenotype for increased IL-1β release from monocytes in response to activation [24] suggesting that similar variation in P2RX7 in microglia may similarly modify cytokine release, leading to neuroinflammation and changing the functional state of neural networks leading to increased vulnerability for mood disorders [23,25], although it is not yet understood how such SNPs increase the risk of mood disorders or, maybe even more importantly, how a loss of function would protect against them [2]. This evidence concerns the gene P2RX7 and mood disorder.