AHCY and hyperhomocysteinemia: It is worth noting that the expression of H19 inhibits S-adenosylhomocysteine hydrolase (SAHH), which hydrolyzes S-adenosylhomocysteine (SAH), which, sequentially, acted as an inhibitor of S-adenosylmethionine (SAM)-dependent methyltransferases, decreased DNA methylation potential caused by hyperhomocysteinemia, and decreased the SAM:SAH ratio [95].