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Apolipoprotein E (Apo E) Genotyping
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Common Questions
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1. My father has been diagnosed with probable late onset AD and his ApoE test is negative for e4 alleles. Should his doctor be doing other genetic testing?
2. I have a 50-year-old brother with Down’s Syndrome who has been diagnosed with probable Alzheimer’s. Does this put me at a higher family risk for AD?
1. My father has been diagnosed with probable late onset AD and his ApoE test is negative for e4 alleles. Should his doctor be doing other genetic testing?
No, not at this time. Forty percent of those who do have late onset AD are negative for ApoE e4 alleles. While genetic mutations of the PSEN1, PSEN2, and APP genes are associated with AD in a very small number of specific family lines, they are associated with early onset AD, not late onset. If your father did not show signs of AD until after the age of 65, then this other genetic testing is not indicated. (If you have a very strong family history of AD, several family members over several generations have had AD, you may want to talk to your father’s doctor about family risk factors).
2. I have a 50-year-old brother with Down’s Syndrome who has been diagnosed with probable Alzheimer’s. Does this put me at a higher family risk for AD?
Not necessarily. Most people who have Down’s Syndrome will eventually have some degree of Alzheimer’s Disease symptoms. Down’s Syndrome is associated with a lifelong overproduction of amyloid precursor protein; a portion of this protein, called amyloid beta 42 peptide (Aß42), is associated with the formation of senile plaques (areas of dead nerve cells and protein deposits in the brain) that are characteristic of AD.
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This page was last modified on
April 16, 2004.
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