Compared with women, men have a shorter life expectancy. The US Centers for Disease Control and Prevention estimate that women live an average of 5 years longer than men. Now, a new study suggests this disparity may be down to a loss of the Y chromosome in blood cells, prompting men to have a shorter life span and higher mortality from cancer.
The researchers publish the results of their latest findings in the journal Nature Genetics.
As part of a national collaboration between four Swedish universities - known as Sciifelab - scientists from Karolinska Institutet, KTH Royal Institute of Technology, Stockholm University and Uppsala University worked together on the study.
The difference in life span among sexes is not unique to the US; the researchers note that around the world, men have a shorter average life span, and incidence and mortality in cancer is higher in men, compared with women.
Although changes in the DNA of normal cells gather during our lives and have been linked to cancer and diabetes, the researchers say the reasons and risk factors behind the differences in life expectancies have been "largely unknown."
To further investigate, the team analyzed the DNA in blood samples from a group of more than 1,600 elderly men.
Loss of Y chromosome linked with shorter survival
The new study suggests the disparity in life expectancy between men and women has to do with loss of the Y chromosome.
The researchers explain that the Y chromosome is only present in men, and that until now, the genes on this chromosome were mostly associated with sex determination and sperm production.
After studying the group of men for many years, the researchers found that the most common genetic alteration was a loss of the Y chromosome (LOY) in a proportion of the white blood cells.
Additionally, the team found a correlation between LOY and shorter survival, irrespective of cause of death.
"We could also detect a correlation between loss of the Y chromosome and risk of cancer mortality," says Lars Forsberg, lead researcher from Uppsala University.
Commenting on their findings, Prof. Jan Dumanski, from the Department of Immunology, Genetics and Pathology at Uppsala University, says:
"You have probably heard before that the Y chromosome is small, insignificant and contains very little genetic information. This is not true. Our results indicate that the Y chromosome has a role in tumor suppression, and they might explain why men get cancer more often than women."
The researchers believe that future analyses of the Y chromosome could "become a useful general marker to predict the risk for men to develop cancer," he adds.
Speaking with Medical News Today, Prof. Dumanski said:
"Loss of Y can already today be considered a strong marker of male carcinogenesis, although our results should be repeated in a much larger cohort; and that is what we are doing."
He added that LOY could become an even stronger marker, "once we identify a specific subpopulation of immune cells which are responsible for its effect on carcinogenesis in other tissues/organs."