Genes that showed the same downwards trend in the AD and COVID-19 groups included FCGR2A, MSR1, TBXAS1, FGL2, GBP2, PLXDC2, MOB3C, PARVG, SYT6, CFD, GALK1, NFKB2, CAPG, PLCG2, APOBR, and C1QA. For example, as a genetic risk factor for AD, FERMT2 controls axonal growth and synaptic plasticity in an APP-dependent manner (38). Here, CFD is linked to COVID-19.