The Y chromosome can disappear over time in human males, increasing their risk of cancer and Alzheimer's disease. And while the exact trigger for such degeneration is unknown, age and environmental factors seem to play a significant role.
Most people have 23 pairs of chromosomes, including a pair of sex chromosomes that can be either X or Y. Having two X chromosomes usually designates a human as biologically female, while having one X and one Y designates a human as male.
The loss of the Y chromosome, or LOY, has "important effects in shaping the activity of the immune system" and can open the door to "cancer, neurodegeneration, cardiovascular disease and acute infection," said a January study published in the journal Nature Reviews Genetics. "As men grow older, they lose this chromosome from many of their cells, which drives age-related disease," said New Scientist.
Y chromosome loss is largely due to "cell division mistakes," said News Medical. That's "enormously common," Lars Forsberg, an associate professor at Uppsala University in Sweden, said to News Medical. And smoking and exposure to environmental toxins can increase the risk.
This research may help explain why women tend to have longer lifespans. Females seem to be the "stronger sex from a genetic point of view, with a more stable and less disease-prone genome," said the study. And as the Y chromosome degrades on the individual level, there's evidence that the chromosome may be going extinct on an evolutionary scale as well. |