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Summary
The test for the gene related to Alzheimer's can usually tell you if you have a higher risk of getting Alzheimer's than average. The test cannot tell you whether you will get the disease - or whether you won't. In this section we explain the test and what you can hope to learn.
Humans have about 25,000 genes. Sometimes there are variations in genes that, when present, can lead to an illness or raise one's chances of developing an illness. In general, genetic tests look for variations related to specific diseases.
Alzheimer's disease can be caused by genes, environmental factors, or some combination of both.
There is one gene that has been associated with late-onset Alzheimer's disease. It is called the Apolipoprotein E gene - or APOE for short.
The APOE gene has three forms: e2, e3, and e4. The e4 form is the one which is associated with a higher risk of Alzheimer's disease. The genetic test can tell which form or forms of the gene are present.
If a person is found to have one copy of the e4 gene, the risk for developing Alzheimer's disease increases. If a person has two copies of the e4 gene, the risk for developing Alzheimer's disease the risk is even higher.
Research is ongoing so we don't know the exact increased risk but currently, it is believed to be as follows.
Each percentage gives the chance of having Alzheimer's by ages 70 and 80.
If the e4 gene is present, a person's risk goes up - but never to 100%.
It's important to keep in mind that:
Researchers believe there are additional genes associated with Alzheimer's that we have not yet identified.
We don't understand all the environmental factors that influence one's susceptibility to Alzheimer's.
