C3 and Alzheimer disease: Similar to C1q, increased C3 CSF levels in advanced AD patients (Finehout et al., 2005; Wang et al., 2011; Daborg et al., 2012) and C3 brain expression in aged AD transgenic mice (Wyss-Coray et al., 2002; Zhou et al., 2008; Reichwald et al., 2009) have been reported.