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Walter Rocca, Prof. of neurology at the Mayo Clinic
says that it is difficult to explain significant geographical variations in the prevalence of Alzheimer's
 real 28k

Monday, 18 June, 2001, 23:03 GMT 00:03 UK
Genetic clue to Alzheimer's risk
Alzheimer's affects 700,000 people in the UK
Alzheimer's affects 700,000 people in the UK
Scientists believe they have found another piece in the genetic jigsaw that predetermines the risk of developing Alzheimer's disease.

Researchers from the US identified a small area of the human genetic make-up, which in addition to a previously identified gene increased the risk of Alzheimer's by 16 times.

That, they say, is greater than the increased risk of developing lung cancer caused by smoking.

These findings mean scientists can look at the particular areas of the human genome to see why they are linked to the increased risk.


It seems likely that genetic risk and environmental factors combine to cause Alzheimer's in individuals

Harry Cayton
Alzheimer's Society
They could lead to the development of new drugs to treat Alzheimer's.

Monitoring

The researchers, from the University of Pittsburgh, followed 300 relatives of 189 Alzheimer's sufferers over 10 years.

The relatives, aged between 40 and 75, were first degree relatives of Alzheimer's patients.

They were assessed to ensure they had not suffered any mental decline before the study began, and were assessed regularly during the trial.

Independently, blind trials of blood samples were genetically tested.

Eighteen people had developed Alzheimer's disease after 11 and a half years.

Further studies in Germany and the US have supported the Pittsburgh findings.

The researchers, led by Dr George Zubenko, found that a small area of Chromosome 10 of human DNA called D10S1423, when combined with a previously identified gene APOE E4, produced the increased risk of developing the disease.

APOE E4 is a gene which codes for a protein that carries fats around the blood.

The study, published in the journal Molecular Psychiatry, also found the newly discovered area also affects levels of dopamine - that is in short supply in Parkinson's patients.

Dr Zubenko and his colleagues wrote: "This may be important in the discovery of drugs or other interventions that have beneficial effects on preventing, forestalling the onset, slowing the progression, or ameliorating the symptoms of dementia in some types of Alzheimer's disease."

Genetic susceptibility

But experts say a very small percentage of cases of Alzheimer's are genetic.

Less than 5% of early-onset disease, and an even smaller percentage of late-onset disease, which this study looked at, are genetic.

And even if people have the risk factors, it does not mean they are certain to develop Alzheimer's.

Harry Cayton, chief executive of the Alzheimer's Society, said: "This is one of a number of susceptibility genes for Alzheimer's disease to have been identified.

"It seems likely that genetic risk and environmental factors combine to cause Alzheimer's in individuals.

"More research will be needed to confirm the results of the Pittsburgh University study."

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See also:

06 Jun 01 | Health
Vaccine hope for Alzheimer's
07 May 01 | Health
Alzheimer's linked to vitamins
24 Apr 01 | Health
10-minute test for Alzheimer's
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