PSEN2 and Alzheimer disease: In the present study, due to the clinical and genetic diversity of AD patients, we screened PSEN1, PSEN2, MAPT, and APP genes in 83 sporadic AD patients, while 53 dementia‐related genes which were screened based on previous studies (He et al., 2017; Hooli et al., 2014; Pottier et al., 2016; Vardarajan et al., 2015) and databases such as OMIM (http://www.omim.org/), Orphanet (http://www.orpha.net/consor/cgi-bin/index.php?lng=EN), and HGMD (http://www.hgmd.cf.ac.uk/ac/index.php) in 25 AD patients with a dementia family history.