C3 KO was shown to be neuroprotective in APP/PS1 transgenic mice (Hong et al., 2016; Shi et al., 2017; Shi et al., 2015) and neurodegenerative in other APP transgenic AD mouse models (Maier et al., 2008; Wyss‐Coray et al., 2002). The gene discussed is APP; the disease is Alzheimer disease.