For example, one study showed that genes associated with AD such as apolipoprotein E (APOE), alpha 2 macroglobulin (A2M), paraoxonase 2 (PON2), and microtubule-associated protein 4 (MAP4), were closely related to genes associated with cardiovascular disease, including catechol-O-methyltransferase (COMT), cystathionine beta synthase (CBS), and WNK lysine deficient protein kinase 1 (WNK1) suggesting both diseases are linked through shared molecular networks (Ray et al., 2008). Here, CBS is linked to Alzheimer disease.