New gene for Alzheimer's risk identified
Researchers have identified a genetic variation that may indicate an increased risk for late-onset Alzheimer’s disease.
The finding is a result of a collaboration between deCODE genetics in Iceland and Emory Alzheimer’s researchers. They read the entire genomes of 2,261 Icelanders.
The new variant increases risk by about a factor of three, an effect that is similar in scope to that of the most common genetic risk factor for Alzheimer’s, ApoE E4. However, the new variant, called TREM2, is rarer: it is found in one in every 160 people in Iceland, compared with more than 17% of the Icelandic population for ApoE E4, a percentage that is higher in other countries. People who carry the variation and do develop Alzheimer’s disease do so roughly three years earlier than non-carriers. Although rare, the variant is important because it adds to a growing list of genes linked to Alzheimer’s disease, and it provides clues to causal mechanisms.
"First, the results demonstrate that certain rare genetic variants can have a strong influence on Alzheimer’s disease risk for individuals carrying those variants," says Allan Levey, director of Emory’s Alzheimer’s Disease Research Center and chair of neurology. "Second, since the TREM2 gene is expressed in microglia and other immune cells where it triggers production of inflammatory cytokines, the finding provides growing evidence that chronic inflammation is relevant for the development of the disease, and that modulating TREM2 signaling and microglial function is a potential therapeutic strategy."
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