Five new genetic variants linked to Alzheimer’s disease
4 April 2011
An international team of researchers led by Professor Julie Williams from Cardiff University analysed combined data from four genome-wide association studies, comparing the DNA of a total of around 20 000 people with Alzheimer's disease against 40 000 healthy controls.
The study, published in 'Nature Genetics', highlights the complexity of Alzheimer's disease, which involves many different genetic variants, each increasing the risk of developing the disease by a small amount.
The discovery of the five new genes has implicated several factors, including the body's immune system, the ways the brain processes cholesterol and lipids, and - for the first time - a process known as endocytosis, which normally removes toxic amyloid-beta protein from the brain.
"What's most exciting [about this study] is a new area of research which refers to a process called endocytosis," explains Professor Williams. "We now have four genes that implicate this very precise process and it offers a very big clue that this process is playing a strong role in the development of Alzheimer's disease."
In 2009, Professor Williams led the largest genetic investigation of Alzheimer's ever conducted, which involved analysing the DNA from more than 16 000 individuals over two years and uncovered new genetic variants closely linked to the illness.
Collaborator Professor Kevin Morgan, from the University of Nottingham, adds: "Until now, the genetics of late-onset Alzheimer's disease have been poorly understood. We are now on the way to identifying all the genetic factors that contribute to [the disease]. This research is already spurring on additional research towards treatments based on specific genetic issues which contribute to the disease."
According to the charity Alzheimer's Research UK, over 825 000 people living in the UK are affected by dementia, of which Alzheimer's is the most common form. As well as the huge personal cost to patients and their families and carers, dementia is estimated to cost the UK economy £23 billion a year, more than cancer and heart disease combined.
"As our population ages, we will see more and more people affected by Alzheimer's disease," says Dr John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, which helped fund this study. "It is distressing both to patients and their families and places a heavy economic burden on our society. Understanding the complex processes that underpin the disease will be essential to earlier diagnosis and to developing improved treatments. This interesting new study takes a step further along this path."
Image: Digital artwork representing the problems of Alzheimer’s disease. Credit: Adrian Cousins, Wellcome Images.
Reference
Hollingworth P et al. Common variants at ABCA7, MS4A6A/MS4A4E, EPHA1, CD33 and CD2AP are associated with Alzheimer's disease. Nat Genet 2011 [epub ahead of print]
