Study Uncovers Why Men have Shorter Life Expectancies
According to United States Centers for Disease Control and Prevention (CDC), on average, women live five years longer than men. For decades, data continuously reveal that men have shorter life spans than women. However, researchers have not been able to explain why this trend exists aside from knowing that cancer tends to kill more men than women. In a new study, researchers suggest that when the Y chromosome, which is only present in males, starts to disappear from certain cells in the body, cancer risk starts to increase.
For this study, the researchers from Uppsala University, Karolinska Institutet, University of Southampton, HudsonAlpha Institute for Biotechnology, University of Oxford, Broad Institute of MIT and Harvard University examined DNA from the blood samples of 1,152 older men in their 70s and 80s from Sweden. The researchers followed the participants over a few years and monitored the relationship between the reduction of the Y chromosome in white blood cells and lifespan.
The team found that at least eight percent of the men had fewer Y chromosome in their bloods cells and at least two percent did not have any Y chromosome left in roughly 35 percent of their blood cells. For these men, they died around 5.5 years earlier than men with more Y chromosome left. These men also had a three-times greater risk of dying from cancer. The researchers concluded that when the Y chromosome disappeared from the cells at a faster rate, survival rates fell.
"Men who had lost the Y chromosome in a large proportion of their blood cells had a lower survival, irrespective of cause of death. We could also detect a correlation between loss of the Y chromosome and risk of cancer mortality", said lead researcher Lars Forsberg, researcher at the Department of Immunology, Genetics and Pathology, Uppsala University, reported in the press release.
The researchers stated that even though they did not find a cause-and-effect relationship, the correlation between the two factors was still strong after they accounted for other variables, such as old age, smoking, weight, diabetes and hypertension.
"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. We believe that analyses of the Y chromosome could in the future become a useful general marker to predict the risk for men to develop cancer", commented researcher, Jan Dumanski, professor at the Department of Immunology, Genetics and Pathology, Uppsala University.
The study, "Mosaic loss of chromosome Y in peripheral blood is associated with shorter survival and higher risk of cancer," was published in Nature Genetics.