A study led by scientists at Lawrence Livermore National Laboratory (LLNL) and the University of California, Berkeley, found a steady increase in sperm DNA fragmentation with increasing age of the study participants, along with increases in a gene mutation that causes achondroplasia, or dwarfism. The first changes were observed in men in their early reproductive years.
Earlier research by the same team indicated that male reproductive ability gradually worsens with age, as sperm counts decline and the sperm lose motility and their ability to swim in a straight line. In the current study, the researchers analyzed DNA damage, chromosomal abnormalities and gene mutations in semen samples from the same subjects 97 healthy, non-smoking LLNL employees and retirees between 22 and 80 years old and found that sperm motility showed a high correlation with DNA fragmentation, which is associated with increased risk of infertility and a reduced probability of fathering a successful pregnancy.
The study, "Advancing age has differential effects on DNA damage, chromatin integrity, gene mutations, and aneuploidies (chromosome abnormalities) in sperm," appears this week in the online edition of the Proceedings of the National Academy of Sciences.
"This study shows that men who wait until they're older to have children are not only risking difficulties conceiving, they could also be increasing the risk of having children with genetic problems," said co-lead author Andrew Wyrobek of LLNL.
"We know that women have a biological time clock," said co-lead author Brenda Eskenazi of UC Berkeley's School of Public Health, "with an increase in risk of miscarriage and producing children with trisomy (an extra ch
Contact: Charlie Osolin
DOE/Lawrence Livermore National Laboratory