Gene mutation defends against Alzheimer’s disease

From Nature:

AlzAlmost 30 million people live with Alzheimer’s disease worldwide, a staggering health-care burden that is expected to quadruple by 2050. Yet doctors can offer no effective treatment, and scientists have not been able definitively to pin down the underlying mechanism of the disease. Research published this week offers some hope on both counts, by showing that a lucky few people carry a genetic mutation that naturally prevents them from developing the condition1. The discovery not only confirms the principal suspect that is responsible for Alzheimer’s, it also suggests that the disease could be an extreme form of the cognitive decline seen in many older people. The mutation — the first ever found to protect against the disease — lies in a gene that produces amyloid-β precursor protein (APP), which has an unknown role in the brain and has long been suspected to be at the heart of Alzheimer’s.

APP was discovered 25 years ago in patients with rare, inherited forms of Alzheimer’s that strike in middle age2–5. In the brain, APP is broken down into a smaller molecule called amyloid-β. Visible clumps, or plaques, of amyloid-β found in the autopsied brains of patients are a hallmark of Alzheimer’s, but scientists have long debated whether the plaques are a cause of the neuro­degenerative condition or a consequence of other biochemical changes associated with the disease. The latest finding supports other genetics studies blaming amyloid-β, and it makes the protein “the prime therapeutic target”, says Rudolph Tanzi, a neurologist at the Massachusetts General Hospital in Boston and a member of one of the four teams that discovered APP’s role in the 1980s.

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