What is the role of APOE in the pathophysiology of Alzheimer disease (AD) in Down syndrome (DS)?

Updated: Nov 13, 2019
  • Author: Norberto Alvarez, MD; Chief Editor: Jasvinder Chawla, MD, MBA  more...
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The gene regulating the apolipoprotein E is considered an important risk factor in the presence of AD in persons without DS. This gene, which has 3 variants (epsilon 2, epsilon 3, epsilon 4), is involved in several functions including cholesterol transport, lipid metabolism, and metabolism of beta-amyloid protein in the brain.

In patients without DS, the APOE epsilon 4 allele is associated with increased risk of AD, and the epsilon e2 allele may be protective. [40, 41, 42] Among patients with DS, several studies have demonstrated that the epsilon e2 allele may be protective. Data suggesting that the e4 allele increases risk in patients with DS are less compelling than the data supporting increased risk for patients without DS. [43]

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