Two studies have identified a rare genetic mutation that boosts the risk of Alzheimer's disease.

Kári Stefánsson of deCODE Genetics in Reykjavik and his group analysed the genomes of 2,261 Icelanders and uncovered a mutation in the TREM2 gene that increased the risk of Alzheimer's disease roughly threefold. A separate research team, led by John Hardy at University College London, discovered the same mutation, along with several others in the same gene, when analysing the genomes of more than 1,000 people with the disease.

The protein encoded by TREM2 is expressed in brain immune cells called microglia, and regulates the process by which these cells engulf cell debris. The findings suggest that, in the brains of people with the neurodegenerative disorder, immune cells are unable to clear away the plaques that are hallmarks of the disease.

N. Engl. J. Med. 368, 107–116; 117–127 (2013)