Breakthrough highlights the role of genes in Alzheimer's

Scientists identify three more genes that increase the risk of getting the most common form of the disease

Scientists have discovered that three known genes play important roles in determining the risk that someone will develop Alzheimer's disease – a finding that could lead to new treatments and a possible early test for one of the most feared disorders of later life.

It is the first time in 15 years that researchers have identified new genetic factors that definitely raise someone's risk of getting the degenerative brain disease.

The breakthrough means that a total of four genes are now known to contribute to Alzheimer's. Scientists hope that further genetic discoveries could soon lead to a diagnostic test that can provide a meaningful assessment of whether someone is likely to develop the condition.

Such a test would help doctors to identify patients at greatest risk of the disease, although it might also be seized upon by insurance companies and other organisations concerned about the cost of long-term healthcare in old age. Alzheimer's disease is one of the fastest growing and most costly medical conditions in the developed world. In Britain, about 700,000 people have some form of dementia including Alzheimer's disease.

This will grow to about 940,000 by 2015, and to more than 1.7 million by 2051, as a result the ageing population.

Two large international teams of researchers announced their findings last night, saying that detailed scans of the entire genomes of a combined total of nearly 20,000 people from eight countries have implicated the three genes, which were already known to play important roles within the brain.

Sir Leszek Borysiewicz, the chief executive of the Medical Research Council (MRC), which part-funded the British study, said the findings, published in the journal Nature Genetics, were crucial in piecing together the complicated picture that can help to explain the Alzheimer's puzzle.

"This study is a huge step towards achieving an earlier diagnosis of Alzheimer's and improving the lives of the many people affected by the disease," Sir Leszek said.

In the British study, carried out at the MRC's Centre for Neuropsychiatric Genetics and Genomics in Cardiff, scientists analysed more than half a million differences in the DNA in each of 4,000 people who had Alzheimer's, and compared them with the DNA of 8,000 people without the disease. A comparable study carried out by the European Alzheimer's Disease Initiative in France compared nearly 4,000 Alzheimer's patients with a comparable number of people who did not have the condition. The British study found two genes and the French found the third, as well as confirming one of the British discoveries.

Professor Julie Williams of Cardiff University, who led one of the research teams, said that the findings are "significant and conclusive" in terms of linking variations in the three genes to the risk of developing Alzheimer's.

"If we were able to remove the detrimental effects of these genes through treatments, we could reduce the proportion of people developing Alzheimer's by 20 per cent," Professor Williams said. "In the UK alone this would prevent just under 100,000 people developing the disease."

The three new genes implicated in Alzheimer's are called CLU, PICALM and CR1. They are the first genes linked to the disease since the discovery 15 years ago of the role of the APOE gene in raising the risk of Alzheimer's.

"Three of the risk genes, APOE, CLU and CR1, have roles in protecting the brain from damage. Perhaps the changes we see in these genes remove this protection or may even turn them into killers," Professor Williams said.

"Our results may highlight new targets for treatments. For example, CLU has a role in dampening down inflammation in the brain," she said.

"Up until now, increased inflammation seen in the brains of Alzheimer's sufferers had been viewed as a secondary effect of disease," she said.

"Our results suggest the possibility that inflammation may be primary to disease development."

Professor Michael Owen, director of the MRC centre said the research will next be expanded it to a full genome-wide analysis of 60,000 volunteers.

This should allow the scientists to pinpoint changes in other genes that play a smaller, yet significant role in raising the risk of Alzheimer's.

The value of this genetic approach to studying Alzheimer's has now been established beyond a doubt, he said.

Alzheimer's: A tangled web

*Alzheimer's disease is a degenerative disorder of the brain and is only truly diagnosed following a post-mortem examination to identify the build-up of protein bundles or tangled "plaques" at the twisted nerve endings of affected brain cells. It is not known whether these tangles or plaques are the cause of all or indeed any of the recognised symptoms of the disease – such as memory loss and cognitive impairment – but they can always be found in the brain of patients who have died of Alzheimer's. It is known that genes play an important role in Alzheimer's. For instance, three genes have been found to explain the rare cases of early-onset Alzheimer's, which is inherited and tends to run in certain families. However, 99 per cent of Alzheimer's patients suffer from the late-onset form of the disease – often called "sporadic" Alzheimer's because it seemingly occurs at random within the population. Nevertheless, it is becoming increasingly clear that even this most common form of the disease has a genetic component, in addition to any environmental factors. Four genes have now been implicated in raising the risk of sporadic, late-onset Alzheimer's. Four variations of the APOE gene, for instance, were identified as a risk factor 15 years ago. Now, three more genes have been added to the list – CLU, PICALM and CR1. It is not yet possible for scientists to give accurate assessments of how much risk each of these genes – or more accurately the variations in the genes – add to a person's chances of getting the disease. However if the effects of the three latest genes were removed from the population as a whole,then something like 100,000 people in Britain alone may be prevented from getting Alzheimer's. Anything that increases our understanding of this debilitating disease, which often results in long-term care, will pay dividends as the population ages significantly in coming decades.

Arts and Entertainment
Flora Spencer-Longhurst as Lavinia, William Houston as Titus Andronicus and Dyfan Dwyfor as Lucius
theatreThe Shakespeare play that proved too much for more than 100 people
News
A 1930 image of the Karl Albrecht Spiritousen and Lebensmittel shop, Essen. The shop was opened by Karl and Theo Albrecht’s mother; the brothers later founded Aldi
people
News
exclusivePunk icon Viv Albertine on Sid Vicious, complacent white men, and why free love led to rape
Arts and Entertainment
booksThe best children's books for this summer
PROMOTED VIDEO
Arts and Entertainment
Stir crazy: Noel Fielding in 'Luxury Comedy 2: Tales from Painted Hawaii'
comedyAs ‘Luxury Comedy’ returns, Noel Fielding on why mainstream success scares him and what the future holds for 'The Boosh'
Life and Style
Flow chart: Karl Landsteiner discovered blood types in 1900, yet scientists have still not come up with an explanation for their existence
lifeAll of us have one. Yet even now, it’s a matter of debate what they’re for
Arts and Entertainment
'Weird Al' Yankovic, or Alfred Matthew, at the 2014 Los Angeles Film Festival Screening of
musicHis latest video is an ode to good grammar. But what do our experts think he’s missed out?
Sport
Colombia's James Rodriguez celebrates one of his goals during the FIFA World Cup 2014 round of 16 match between Colombia and Uruguay at the Estadio do Maracana in Rio de Janeiro, Brazil
sportColombian World Cup star completes £63m move to Spain
Arts and Entertainment
Standing the test of time: Michael J Fox and Christopher Lloyd in 'Back to the Future'
filmA cult movie event aims to immerse audiences of 80,000 in ‘Back to the Future’. But has it lost its magic?
Life and Style
News to me: family events were recorded in the personal columns
techFamily events used to be marked in the personal columns. But now Facebook has usurped that
News
news
News
i100
News
ebookA unique anthology of reporting and analysis of a crucial period of history
News
people
Sport
Antoine Griezmann has started two of France’s four games so far
sport
Life and Style
techYahoo Japan launches service to delete your files and email your relatives when you die
Life and Style
Child's play: letting young people roam outdoors directly contradicts the current climate
lifeHow much independence should children have?
Arts and Entertainment
Tycoons' text: Warren Buffett and Bill Gates both cite John Brookes' 'Business Adventures' as their favourite book
booksFind out why America's richest men are reading John Brookes
Independent
Travel Shop
the manor
Up to 70% off luxury travel
on city breaks Find out more
santorini
Up to 70% off luxury travel
on chic beach resorts Find out more
sardina foodie
Up to 70% off luxury travel
on country retreats Find out more
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Sustainability Manager

Competitive: The Green Recruitment Company: Job Title: Scheme Manager (BREEAM)...

Graduate Sustainability Professional

Flexible, depending on experience: The Green Recruitment Company: Job Title: T...

Programme Director - Conduct Risk - London

£850 - £950 per day: Orgtel: Programme Director - Conduct Risk - Banking - £85...

Project Coordinator/Order Entry, SC Clear

£100 - £110 per day: Orgtel: Project Coordinator/Order Entry Hampshire

Day In a Page

Noel Fielding's 'Luxury Comedy': A land of the outright bizarre

Noel Fielding's 'Luxury Comedy'

A land of the outright bizarre
What are the worst 'Word Crimes'?

What are the worst 'Word Crimes'?

‘Weird Al’ Yankovic's latest video is an ode to good grammar. But what do The Independent’s experts think he’s missed out?
Can Secret Cinema sell 80,000 'Back to the Future' tickets?

The worst kept secret in cinema

A cult movie event aims to immerse audiences of 80,000 in ‘Back to the Future’. But has it lost its magic?
Facebook: The new hatched, matched and dispatched

The new hatched, matched and dispatched

Family events used to be marked in the personal columns. But now Facebook has usurped the ‘Births, Deaths and Marriages’ announcements
Why do we have blood types?

Are you my type?

All of us have one but probably never wondered why. Yet even now, a century after blood types were discovered, it’s a matter of debate what they’re for
Honesty box hotels: You decide how much you pay

Honesty box hotels

Five hotels in Paris now allow guests to pay only what they think their stay was worth. It seems fraught with financial risk, but the honesty policy has its benefit
Some are reformed drug addicts. Some are single mums. All are on benefits. But now these so-called 'scroungers’ are fighting back

The 'scroungers’ fight back

The welfare claimants battling to alter stereotypes
Amazing video shows Nasa 'flame extinguishment experiment' in action

Fireballs in space

Amazing video shows Nasa's 'flame extinguishment experiment' in action
A Bible for billionaires

A Bible for billionaires

Find out why America's richest men are reading John Brookes
Paranoid parenting is on the rise - and our children are suffering because of it

Paranoid parenting is on the rise

And our children are suffering because of it
For sale: Island where the Magna Carta was sealed

Magna Carta Island goes on sale

Yours for a cool £4m
Phone hacking scandal special report: The slide into crime at the 'News of the World'

The hacker's tale: the slide into crime at the 'News of the World'

Glenn Mulcaire was jailed for six months for intercepting phone messages. James Hanning tells his story in a new book. This is an extract
We flinch, but there are degrees of paedophilia

We flinch, but there are degrees of paedophilia

Child abusers are not all the same, yet the idea of treating them differently in relation to the severity of their crimes has somehow become controversial
The truth about conspiracy theories is that some require considering

The truth about conspiracy theories is that some require considering

For instance, did Isis kill the Israeli teenagers to trigger a war, asks Patrick Cockburn
Alistair Carmichael: 'The UK as a whole is greater than the sum of its parts'

Alistair Carmichael: 'The UK as a whole is greater than the sum of its parts'

Meet the man who doesn't want to go down in history as the country's last Scottish Secretary