FCGR2B and acute respiratory distress syndrome: First of all, there are all six human genes in the figure, FCGR1A, FCGR2A, FCGR2B, FCGR2C, FCGR3A, and FCGR3B, homologous to the rat Fcgr2b gene identified as a molecular marker for elevated neuropathic pain tolerance in ARDs.