Scientists discover rare genetic mutation that protects against Alzheimer’s

Researchers studying the DNA of nearly 2,000 people discover a new, protective mutation.

Posted on 11th July 2012

A new study reports the discovery of a rare genetic mutation that protects against Alzheimer’s disease and cognitive decline associated with getting older. The study is published online on 11 July in the journal Nature.

The research team, made up of scientists from across Europe and the US, studied the DNA of 1,795 people from Iceland. They looked for subtle genetic changes – so called mutations – which might alter the function of particular genes and influence a person’s risk of developing Alzheimer’s.

The scientists looked specifically for changes in a gene called APP, which codes for a protein called the ‘amyloid precursor protein’. This protein is found normally in the brain and is cut up into smaller proteins, including one called amyloid. In Alzheimer’s disease, amyloid starts to build into clumps called plaques which can lead to the death of nerve cells.

Previous research has found rare inherited mutations in APP which could drive Alzheimer’s disease by causing too much amyloid to be produced but until now no protective mutations have been found. The researchers discovered a rare mutation in the APP gene, present in only around 3 out of every 1000 people, which protected people against Alzheimer’s disease and from age-related memory and thinking problems.

The researchers found that the mutation led to a change in the stretch of the APP protein that is normally cut up to make amyloid. In people with the mutation, there was around 40% reduction in the amount of toxic amyloid produced.

Dr Eric Karran, Director of Research at Alzheimer’s Research UK, said:
“This study has discovered a rare mutation that protects those who carry it from Alzheimer’s disease. While only very few of us are likely to have the mutation, the findings have important implications for research into Alzheimer’s and the development of future treatments.

“The mutation reduces the amount of the amyloid protein in the brain, which is known to build up into damaging plaques in Alzheimer’s disease. The discovery supports a common concept in Alzheimer’s research – that new treatments aimed at reducing amyloid could be effective in preventing the development of the disease, if given early enough.

“Although this finding is significant, there is a still a long way to go before such treatments may be available. We must keep up the momentum and continue to invest in research to translate these findings into effective treatments for the thousands of people affected by this devastating disease.”

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