No one knows for certain what causes Alzheimer’s disease. But one fact about the condition has gained nearly irrefutable status. Depending on what versions of a gene called APOE you inherit, your risk of the brain disorder can be half the average—or more than 12 times as high.
Sometimes called “the forgetting gene,” APOE comes in three common versions, called 2, 3, and 4. Type 2 lowers a person’s risk, 3 is average, and 4 increases the chance dramatically. The risk is so great that doctors avoid testing people for APOE because a bad result can be upsetting, and there’s nothing to do about it. There’s no cure, and you can’t change your genes, either.
Well, today you can’t. But doctors in New York City say that beginning in May, they will start testing a novel gene therapy in which people with the unluckiest APOE genes will be given a huge dose to their brain of the low-risk version.