SNCA and Alzheimer disease: We screened for 12 AD‐PD genes consisting of three genes previously reported to contain mutations robustly associated with PD (SNCA, LRRK2, and VPS35) and nine genes associated with PD with low confidence (GIGYF2, EIF4G1, DNAJC13, CHCHD2, HTRA2, NR4A2, RIC3, TMEM230, and UCHL1) in 191 Chinese sporadic PD patients and 200 unrelated controls.