MTHFR and hypertensive disorder: Among hundreds of genes potentially involved in AD pathogenesis and concomitant disorders (cardiovascular and cerebrovascular disorders, hypercholesterolemia, and hypertension), at least four categories of genes deserve special attention: (i) genes associated with lipid metabolism (APOB, APOC3, APOE, CETP, and LPL), (ii) genes associated with endothelial function and hypertension (NOS3, ACE, and AGT); (iii) genes associated with immune function and inflammation (IL1B, IL6, IL6R, and TNFA); and (iv) genes associated with thrombosis and coagulation (F2, F5, and MTHFR) [17,36,39].