One function of all these genes is to break down cholesterol in the body. The link between the apoE genes and cholesterol breakdown explains why E4, which isn't much good at disposing of cholesterol, has been linked to heart problems. High cholesterol leads to plaque on artery walls. The plaque narrows the passage of blood through an artery just as lime buildup blocks the flow of water through pipes. When the artery gets too narrow, or entirely clogged, people get heart pains, attacks and failures.
People inherit apoE genes from their parents.
They get one copy of the gene from each parent. It's genetic roulette, and the consequences can be devastating. For example, inheriting two copies of the apoE4 gene, one from each parent, can increase the risk of heart disease by 30 to 50 percent. Now comes DeCarli's finding that having one copy of the gene makes it more likely a person will have a stroke. He said he's not sure about the effect of carrying two copies of the gene.