People we meet at Genetic Support Foundation often have questions about the genetic aspects of dementia and Alzheimer\u2019s disease. They wonder if Alzheimer\u2019s disease can run in the family. They wonder what their chance to develop Alzheimer’s disease is. They wonder what genetic testing for Alzheimer\u2019s disease is available and what it can reveal. <\/p>\n\n\n\n
As with many things in genetics, there are no one-size-fits-all answers to these questions. Reviewing your family and health history as well as your personal beliefs and goals with a genetic counselor can help you understand the current state of information we have with regards to genetics and Alzheimer\u2019s disease and how this applies to your unique situation.<\/p>\n\n\n\n
Our understanding of the genetic contributions of Alzheimer\u2019s disease is increasing but we still have much to learn. In most cases, it seems that Alzheimer\u2019s disease is multifactorial, which means there are both genetic and environmental factors at play, and for the most part we still don\u2019t have a great understanding of what all of those factors are.<\/p>\n\n\n\n
About 25% of Alzheimer\u2019s disease is considered familial,<\/em> which means that there are 3 or more people in the same family with Alzheimer\u2019s disease. This means that in most cases (~75% of the time) when someone is diagnosed with Alzheimer\u2019s disease, there is not a strong family history. Late Onset Alzheimer’s Disease<\/strong><\/em><\/p>\n\n\n\n The average lifetime risk for a person to develop Alzheimer\u2019s disease is 10-12%, and the vast majority (95%) of Alzheimer\u2019s disease is considered \u201clate onset\u201d, which is defined as being diagnosed sometime after the age of 60-65. If you have one first degree relative with late onset Alzheimer’s disease, your risk is to develop Alzheimer\u2019s disease is approximately 20-25%, which is about two times higher than the average risk.<\/p>\n\n\n\n There have been several genetic factors identified that may slightly increase the odds of developing Alzheimer\u2019s disease. One of the most frequently studied genes related to Alzheimer\u2019s disease risk is APOE. <\/em>The APOE <\/em>gene codes for the protein apolipoprotein E, which is important for cholesterol metabolism in the body. There are three common different versions (aka \u201calleles\u201d) of the APOE<\/em> gene known as e2, e3, and e4. Each of us inherits one copy of the APOE<\/em> gene from each biological parent. Studies have shown that people who inherit the e4 version of the APOE<\/em> gene have a higher chance to develop Alzheimer\u2019s disease than those who do not. Individuals who inherit an APOE<\/em> e4 gene from both<\/em><\/strong> parents have about a 25%-35% chance to develop Alzheimer\u2019s disease by age 75.<\/p>\n\n\n\n
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