A rare genetic mutation protects a man from Alzheimer's

Scientists have discovered a second person who should have had symptoms of Alzheimer's disease in his early forties, but did not. His condition joins one identified several years ago with a genetic mutation that is thought to have played a role in delaying the onset of signs of her underlying Alzheimer's disease. The Colombian man retired in his early sixties, and only then, years later, at the age of sixty-seven, did the first signs of cognitive decline appear.

Scans revealed that his brain had atrophied and was loaded with the classic molecular features of the disease, however, the man resisted Alzheimer's for much longer than expected. It turns out that in addition to the genetic variant he predicted, the man also carried a rare variant in another gene that encodes a protein called Raylen, which appears to protect him from Alzheimer's for more than two decades.

In a small specific part of his brain where neurons are involved in memory and mobility, the man had very low levels of synaptic tao. It was as if the genetic lottery had given him a protective protein that prevented Alzheimer's disease in this critical brain region.