Loss of Y chromosome may up Alzheimer's risk: study

Men with blood cells that do not carry the Y chromosome are at greater risk of developing Alzheimer's disease, according to a new study that may lead to a simple test to diagnose the nuerodegenerative disorder.
The loss of the Y chromosome (LOY) is known to affect up to 20 per cent of men who are aged over 80, and is the most common genetic mutation acquired during a man's lifetime.
Lars Forsberg and Jan Dumanski from Uppsala University in Sweden and colleagues investigated loss of the Y chromosome in over 3,200 men with an average age of 73, and an age range of 37-96. Around 17 per cent of them showed LOY in blood cells, and this increased with age.

The researchers found that those with an existing diagnosis of Alzheimer's disease (AD) had a higher degree of LOY, and that LOY was also a marker for the likelihood of developing the disease during the follow-up period.
Using standard molecular techniques, the identification of LOY in blood is easy to determine when it occurs in 10 per cent or more of blood cells with a nucleus containing DNA. As well as being relatively common in older men, it also occurs less frequently in those who are younger.
Since women do not carry a Y chromosome, and men have, on average, shorter lives, it is possible that LOY may be related to the earlier death of men, researchers said.

However, the mechanisms and causes for their findings are still not properly understood, they said.

Researchers are currently investigating the functional effects of LOY, and looking at its role in different groups of men and in other diseases, in order to understand better which types of cancer are associated with LOY, as well as whether there is a link with early signs of dementia, for example mild cognitive impairment.
"The blood cells we studied are involved in the immune system, and the fact that LOY in them is associated with disease in other tissues is striking. We therefore hypothesise that the loss of LOY in blood cells leads them to lose part of their immune function,' said Dumanski.

Diagnosis and treatment of serious conditions such as AD and cancer is currently based on identifying clinical symptoms.
Development of diagnostic tools for their earlier detection could lead to strategies aimed at preventing the diseases before symptoms occur.
In the future it might be possible to use an LOY test to identify men at risk and then carry out oncological or neurological evaluations to try to detect early, mild, symptoms of disease.
LOY might also become an important diagnostic tool in combination with other biomarkers that may be used to predict risks for various diseases.
The research was published in the American Journal of Human Genetics.