Mice deficient in ECE-1 or NEP show elevated levels of the Aβ peptide (Iwata et al., 2001; Eckman et al., 2003, 2006; Madani et al., 2006; Rodriguiz et al., 2008; Walther et al., 2009), and some polymorphisms in these genes have been associated with risk of developing AD (Marr and Spencer, 2010; Pacheco-Quinto et al., 2013). Here, ECE1 is linked to Alzheimer disease.