PSMA4 and Alzheimer disease: Furthermore, we selected the top 10 genes of the AD_PPI network connectivity as the major genes of AD, among which, SNRPD2, RPS3A, S100A8, SNRPG, LSM3, TXN, PSMA4, ANXA1, DNAJA, and PFDN5 were not only major pathogenic genes of AD, but also bridge genes (Table 1).