In addition to the hallmarks of AD (i.e., amyloid beta peptide and tau protein), several other molecules have the potential to become useful biomarkers, including lipocalin 2 (LCN2), an acute-phase protein involved in iron homeostasis (Mesquita et al., 2012, 2014; Ferreira et al., 2013). This evidence concerns the gene LCN2 and Alzheimer disease.