Specifically, the researchers found damage in the sperm's RNA transcripts. The conversion of DNA to RNA is the first step in the process of gene expression, that is, the production of a cellular end-product (such as a protein) from an original DNA precursor. Even more interesting was the type of genes involved. The researchers found that genes important in DNA repair were affected, thereby diminishing the cell's ability to repair sperm DNA after damage has occurred.
Sperm DNA damage has been shown to lead to decreased embryo viability as well as some childhood illnesses, including some cancers.