sperm

Genetic mutations that can cause disease become increasingly common in sperm as men grow older, and new evidence suggests this happens because certain DNA changes are actually favored during sperm production, according to new research.

In a major study published on October 8 in Nature, scientists from the Wellcome Sanger Institute and the TwinsUK study at King's College London mapped how harmful DNA mutations accumulate across the entire sperm genome as men age.

Until recently, however, scientists lacked the precise tools to measure how strongly certain mutations are favored in sperm.

The data revealed that about 2 percent of sperm from men in their early 30s carried disease-causing mutations.

Among 70-year-old participants, 4.5 percent of sperm contained harmful mutations, showing a clear link between age and genetic risk to offspring.