Gene mutation finding suggests immune system role in Alzheimer's

They looked at the complete genomes of 281 patients with Alzheimer's and 504 who didn't have it, including 175 elderly people. When they found a "disproportionate number of variants" in the TREM2 of people with the disease, they expanded the research and used other sequencing and study techniques to look at more than 1,000 individuals with Alzheimer's, as well as that many without. All were of European and North American descent.

They also reached out to other centers and experts to look at TREM2 in various ways, from mice with human mutations known to cause the disease, to other ways of replicating the association. It was clear that TREM2 is one of the genes that changes the most in its expression between normal mice and mice with Alzheimer's, Kauwe said. They also looked at brain sections of people who had the mutation to see that they "did have clean, clear-cut, diagnosable Alzheimer's disease, which they did."

They confirmed what they found in a still-broader base, analyzing data from 6,675 people with Alzheimer's and 16,242 without. One variant of TREM2, called R47H, had a particularly strong association with the disease.

A release from London said the TREM2 gene "controls a protein that is involved in regulating the immune response to injury or disease, acting as an on/off switch for immune cells in the brain called microglia. The R47H variant of the gene results in a partial loss of this function, with less ability to keep cell activity in check, "potentially causing them to become hyperactive."

Other centers involved in the research were the Mayo Clinic, University of Toronto, U.S. National Institute of Aging, King's College London, University of Nottingham, Tanz Centre for Research in Neurodegenerative Diseases, Istanbul University, Utah State University, University of Coimbra, Medical University of Lodz, University of Perugia, University of Kuopio, Aristotle Univesity of Thessaloniki, Hospital La Grave-Casselardit, University of Manchester, Universite Lille Nord de France, Cardiff University and University of Cambridge.

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