A simple blood test to identify if men have lost crucial genetic material in later life could finally close the gap in life expectancy between men and women, scientists believe. New research shows that when men lose their Y chromosome they are hundreds of times more likely to develop Alzheimer's disease.Previous research has shown that smoking hugely increases the risk of losing the Y chromosome, suggesting the missing genetic material may also be linked to cancer.The widespread use of testing could radically decrease male mortality rates, and even perhaps eliminate the difference in life expectancy between the sexes.It is thought that the Y chromosome is crucial for the normal function of the immune system and without it the body struggles to eliminate cancerous cells, and amyloid plaques in the brain which cause Alzheimer's disease. The missing chromosome could be responsible for illnesses that prevent men living as long as women.Now scientists at Uppsala University in Sweden have found it is possible to test for its loss in a breakthrough which could lead to widespread screening to pick up which men are at risk of disease so that the appropriate interventions can be made.The loss of the Y chromosome is known to affect up to 20% of men who are aged over 80, and is the most common genetic mutation acquired during a man's lifetime...