MTHFR and Alzheimer disease: Of particular interest here, Mthfr polymorphisms that result in mild MTHFR deficiency have been identified as a risk factor for AD in selected populations (Wang et al., 2005, 2008; Kageyama et al., 2008; Hua et al., 2011; Coppede et al., 2012; Mansouri et al., 2013).