Study Reveals Aging in Men Affects Sperm DNA and Disease Risk
New research indicates that as men age, potentially harmful DNA mutations accumulate in their sperm, which may increase the likelihood of passing these mutations to their children and consequently affect disease risks in the next generation.
DNA mutations happen during cell replication, either by chance or due to environmental factors. These mutations can disrupt bodily functions or remain inconsequential. Similar to how a car experiences wear and tear, mutations build up over time; however, the specific effects of these mutations on sperm in older men have been somewhat unclear.
Researchers from the Wellcome Sanger Institute and King’s College London utilized a sophisticated analysis method known as NanoSeq to investigate mutations in sperm from men aged 24 to 75, along with identifying the genes impacted.
Interestingly, they discovered that mutation rates rise with age. Some mutations are described as ‘selfish‘, providing cells with a growth advantage that allows them to outpace other cells in the testes, eventually dominating. A number of these mutations have previously been associated with developmental disorders and cancers.
“We anticipated finding some level of selection driving mutations in sperm,” noted geneticist Matthew Neville. “What caught us off guard was the extent to which the number of sperm carrying serious disease-related mutations increased.”
The team examined 81 samples from 57 healthy men, including twins, allowing them to distinguish between age-related mutations and heritable genetic factors.
They found that about 2 percent of sperm from men in their 30s bore mutations that could lead to disease. This figure rose to 3-5 percent among middle-aged and older men (over 43), with an average of 4.5 percent of sperm from men at age 70 exhibiting potentially harmful mutations.
Moreover, the research identified 40 genes influenced by the ‘selfish’ mutant cells becoming prevalent in the positive selection dynamic within the testes. This could assist in future studies linking specific mutations to particular disease vulnerabilities.
“Some modifications in DNA not only persist but thrive in the testes, suggesting that fathers who conceive later in life might unknowingly carry a higher risk of transmitting harmful mutations to their offspring,” remarked geneticist Matt Hurles.
However, it’s crucial to remember that not all mutations will necessarily be inherited. Some could reduce reproductive success—for instance, by adversely affecting embryo development.
Further research is needed to understand how this increasing array of DNA mutations in men influences the health of their children. Nonetheless, this study sheds significant light on the processes at play.
These findings provide valuable insights into the male germline, which refers to the cells dedicated to passing genetic information to the next generation, with all its possible advantages and downsides.
“The male germline is a complex setting where natural selection might favor harmful mutations, occasionally affecting subsequent generations,” noted geneticist Raheleh Rahbari.
The results of this research were published in Nature.
