Mutant gene stops at-risk people from getting Alzheimer's
The APOE4 gene is the most powerful genetic factor driving a person's risk for developing late-onset Alzheimer's disease. An international research team led by Greicius has discovered a rare mutation that actually negates the Alzheimer's risk posed by the APOE4 gene.

The R251G variant changes just a single amino acid in the apolipoprotein E (APOE) gene, but that simple alteration appears to neutralize the Alzheimer's risk normally caused by APOE4. Unlike most people with APOE4, people with the R251G mutation have no increased risk of developing Alzheimer's.

Researchers mined huge sets of genetic data that included more than 544,000 people. These included gene analysis of more than 67,000 people with Alzheimer's, 28,000 people who have an immediate family member with Alzheimer's, and 340,000 healthy people to compare them against.

Everyone carries a version of the APOE gene, which mainly helps manage the use of cholesterol around the body. Cholesterol is important for normal cell function, as a key ingredient in cell walls.