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Women-only gene link to dementia | Women-only gene link to dementia |
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Scientists have found a genetic risk factor for late onset Alzheimer's disease which is carried only by women. | |
The discovery is the first evidence to suggest that genetics may partly explain why more women than men tend to develop the disease. | The discovery is the first evidence to suggest that genetics may partly explain why more women than men tend to develop the disease. |
The key variant was found in a gene on the X chromosome, of which females have two copies, but males only one. | The key variant was found in a gene on the X chromosome, of which females have two copies, but males only one. |
The study, by the US-based Mayo Clinic College of Medicine, features in the journal Nature Genetics. | |
The cause of Alzheimer's is unknown, but it is likely that a mixture of environmental and genetic factors is involved Rebecca WoodAlzheimer's Research Trust The Mayo team carried out a detailed genetic analysis of patients with Alzheimer's diease. | The cause of Alzheimer's is unknown, but it is likely that a mixture of environmental and genetic factors is involved Rebecca WoodAlzheimer's Research Trust The Mayo team carried out a detailed genetic analysis of patients with Alzheimer's diease. |
They identified a particular variant of a gene called PCDH11X which appeared to be closely linked to a higher risk of the disease. | They identified a particular variant of a gene called PCDH11X which appeared to be closely linked to a higher risk of the disease. |
However, further analysis showed that the association was almost entirely restricted to women. | However, further analysis showed that the association was almost entirely restricted to women. |
The raised risk of Alzheimer's was not statistically significant in men who carried one copy of the rogue gene variant, and only marginally so in women with just one copy. | The raised risk of Alzheimer's was not statistically significant in men who carried one copy of the rogue gene variant, and only marginally so in women with just one copy. |
But the raised risk was much more significant in women who carried two copies - one inherited from each parent. | But the raised risk was much more significant in women who carried two copies - one inherited from each parent. |
Cell communication | Cell communication |
PCDH11X controls production of a protein called a protocadherin, part of a family of molecules that help cells in the central nervous system to communicate with each other. | PCDH11X controls production of a protein called a protocadherin, part of a family of molecules that help cells in the central nervous system to communicate with each other. |
Some evidence has suggested that protocadherins may be broken down by an enzyme which has been linked to some forms of Alzheimer's disease. | Some evidence has suggested that protocadherins may be broken down by an enzyme which has been linked to some forms of Alzheimer's disease. |
Lead researcher Dr Steven Younkin said it was likely that many genes contributed to the overall risk of Alzheimer's, and that age was probably a more significant factor. | Lead researcher Dr Steven Younkin said it was likely that many genes contributed to the overall risk of Alzheimer's, and that age was probably a more significant factor. |
He said: "It is exciting to find a new gene for Alzheimer's, particularly the first that has a gender-specific effect, but we have a lot more work to do to resolve the complex genetics of the disease." | He said: "It is exciting to find a new gene for Alzheimer's, particularly the first that has a gender-specific effect, but we have a lot more work to do to resolve the complex genetics of the disease." |
Rebecca Wood, of the Alzheimer's Research Trust, described the research as "important". | Rebecca Wood, of the Alzheimer's Research Trust, described the research as "important". |
She said: "Finding genes associated with Alzheimer's will tell researchers about the biology of the disease, which could lead to new treatments being developed. | She said: "Finding genes associated with Alzheimer's will tell researchers about the biology of the disease, which could lead to new treatments being developed. |
"At present, the cause of Alzheimer's is unknown, but it is likely that a mixture of environmental and genetic factors is involved. | "At present, the cause of Alzheimer's is unknown, but it is likely that a mixture of environmental and genetic factors is involved. |
"Two thirds of people with dementia are women, but this is partly because women live longer and risk of developing dementia increases with age." | "Two thirds of people with dementia are women, but this is partly because women live longer and risk of developing dementia increases with age." |
Neil Hunt, of the Alzheimer's Society, said research by his organisation showed that twice as many women than men over 65 have dementia. | Neil Hunt, of the Alzheimer's Society, said research by his organisation showed that twice as many women than men over 65 have dementia. |
"It is likely that a combination of factors cause Alzheimer's disease. Genetics play a part, but whilst dementia isn't a natural part of ageing, age is the biggest risk factor." | "It is likely that a combination of factors cause Alzheimer's disease. Genetics play a part, but whilst dementia isn't a natural part of ageing, age is the biggest risk factor." |
It is estimated that 700,000 people in the UK have dementia. | It is estimated that 700,000 people in the UK have dementia. |