PSEN1 and Alzheimer disease: In this study, four novel variants were identified, which expanded the mutational spectrum of PSEN1. The AAO of PSEN1 mutation carriers in our study (47.5 years), was older than Ryan et al. reported (43.6 years) in 168 AD patients with PSEN1 mutations22, but younger than Jia et al. reported in a large FAD cohort from China (50.59 years)23.