FCGR2B and Alzheimer disease: Because the interaction of Aβ species, especially oligomeric Aβ1-42, with FcγRIIb accounts for such neuropathogenic defects of AD as an initiation step, the selective interaction of oligomeric Aβ1-42 with FcγRIIb may hint at why Aβ1-42, but not Aβ1-40, is important in tau pathology (Oddo et al., 2008; Kam et al., 2013).