New research reveals that as men age, their sperm accumulate more DNA mutations, some of which may increase the risk of passing on genetic disorders to their children.
Mutations arise naturally when cells replicate or due to environmental factors. While some mutations have no noticeable effect, others can disrupt normal development or increase disease susceptibility. Until now, the extent to which these genetic changes affect sperm in older men was not fully understood.
Scientists from the Wellcome Sanger Institute and King’s College London used a cutting-edge technique called NanoSeq to examine sperm DNA from men aged 24 to 75. Their analysis focused on both the number of mutations and the specific genes affected.
The study found that mutation rates rise significantly with age, and some mutations are “selfish,” meaning they give sperm cells a growth advantage. These cells replicate faster and gradually dominate the testes. Many of these mutations have been previously associated with developmental disorders and cancers.
Geneticist Matthew Neville from the Wellcome Sanger Institute said, “We expected some evidence of selection shaping mutations in sperm, but the extent to which it increases the number of sperm carrying disease-linked mutations was surprising.”
The team analyzed 81 sperm samples from 57 healthy men, including some twins, allowing researchers to separate the effects of aging from inherited genetic factors. This study sheds new light on how paternal age can influence genetic risks for the next generation.
