“Mutated Sperm” Could Be Behind Genetic Disorders, Researchers Say

Sperm cells are like any other cells in the body. They form based on instructions in our DNA, and sometimes, like with any process that happens millions and millions of times, there is the occasional error. These errors result in a very small amount of cells becoming “mutated sperm”—a process that researchers at Oxford now say is more and more common as men age.

Certain mutations in sperm cells, though rare in early life, proliferate over time, resulting in a cascade effect that results in more of these problematic sperm later on. Typically, a man has a four in 200 chance of passing down a genetic disorder to his children, but after the age of 50, that number jumps to five in 200. The new study now appears in PNAS.

That’s an increase of 25% over men under 50. Of course, a 2% chance of passing on a genetic disorder is slim to begin with, but statistically, the risk is a significant one. This increase is partially owed to the fact that mutated sperm can sometimes generate an error in their DNA that actually allows them to copy themselves at a rate that outpaces normal sperm production. In other words, it’s all downhill after 50.