The Genetics Behind Alzheimer's Disease

By Elizabeth Stannard Gromisch HERWriter

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Alzheimer's disease can be a devastating disease for the patient and her family. As the disease progresses, patients lose their cognitive skills and abilities to take care of themselves. Each year, Alzheimer's disease costs $172 billion, according to the Alzheimer's Association's 2010 figures. But is Alzheimer's disease genetic? People who have a relative with the disease have a higher risk of developing it themselves. MedlinePlus, a service of the U.S. National Library of Medicine and the National Institutes of Health, notes that the risk of Alzheimer's disease increases with having a blood relative with the disease. One type of Alzheimer's disease, early onset Alzheimer's disease, appears to run in families as well.

Researchers have identified several genes linked to Alzheimer's disease. For early Alzheimer's disease, patients may have familial Alzheimer's disease, which has different chromosome mutations. The National Institute on Aging explains that patients with this type of Alzheimer's disease have mutations on chromosomes 1, 14 and 21: the chromosome 1 mutation results in abnormal presenilin 2, the chromosome 14 mutation results in abnormal presenilin 1, and the chromosome 21 mutation causes abnormal amyloid precursor protein to be formed. The inheritance pattern for familial Alzheimer's disease is autosomal dominant.

But what about late onset Alzheimer's disease? In this more common form of Alzheimer's disease, patients start having symptoms after age 65. But patients who have this type of Alzheimer's disease may also have a genetic component. The MayoClinic.com lists three types of the gene apolipoprotein E (APOE) and their relation to late onset Alzheimer's disease: APOE e3. APOE e4 and APOE e2. The most common type of APOE, APOE e3 does not appear to affect the risk of Alzheimer's disease. APOE e2, the least common type of APOE, seems to reduce the risk of the disease, while APOE e4, which is slightly more common than APOE e2, seems to increase the risk of the disease. About 40 percent of patients with late onset Alzheimer's disease have APOE e4, adds the National Institute on Aging. While a blood test for APOE does exist, it cannot predict yet who will develop Alzheimer's disease.

Some other genes may also be involved in Alzheimer's disease. For example, some types of the SORL1 gene may increase beta-amyloid production, according to the MayoClinic.com. People who have a deficit of the protein produced by the gene CR1 may have brain inflammation, which may factor into the disease development.

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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.