High risk of Alzheimer's disease linked to newly discovered gene mutation

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Scientists in two different studies identified what is now only the second known gene mutation suspected to increase the likelihood of Alzheimer's disease in senior citizens.

The research teams and their work, both profiled in The New York Times, focused on the mutated TREM2 gene. While they aren't quite sure how yet, they believe it blocks the body's ability to generate effective white blood cells in the brain that will eat up beta amyloid, the protein blamed for building up plaque that leads to Alzheimer's. Research teams from University College London and deCODE Genetics of Iceland reached the same conclusion, both from wildly different starting points. Details of each team's work are published in The New England Journal of Medicine.

As the article notes, the discovery is a pretty big deal. Drug developers could theoretically develop treatments targeted to the mutated gene to restore it to proper function. But there's a catch. The TREM2 mutation apparently takes place in 2% of Alzheimer's patients at best. The researchers themselves note that its rareness makes it impractical to start screening patients for the mutation. And even if a personalized drug can be developed, that would be years away. (ApoE4 is the other known gene that mutates in Alzheimer's patients and is more common, according to the story.)

The University College London team, led by John Hardy, began their research by looking at patients with a rare disease that involved crumbling bones and an abnormal variation of dementia, with a TREM2 mutation. The deCODE Genetics team in Iceland, led by Kári Stefánsson, studied the genomes of 2,261 Icelanders and zeroed in on TREM2. Their finding: Patients with Alzheimer's more often had that mutation, as did patients not formally diagnosed but with failing memories, the story explains.

- read the NYT story (sub. req)
- here's the deCODE Genetics article abstract
- check out the University College London abstract

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