You have grandpa’s chromosome tips

Older fathers pass more gene-protecting DNA to their paternal grandkids

Men who become fathers later in life may pass a mark of longevity down to their paternal grandchildren.

As men age, chromosomes in their sperm are tipped with longer telomeres — structures that protect valuable genetic information from deterioration during cell division and other processes. Longer telomeres have been associated with long life, whereas short telomeres have been linked to aging and disease.  

Scientists have known for a while that telomeres increase in length for every year a man ages and that children of older dads inherit longer telomeres. But the new study by researchers at Northwestern University in Evanston, Ill., extends that inheritance to grandchildren. The new finding, published online June 11 in the Proceedings of the National Academy of Sciences, could point to a mechanism by which men can influence the health of their offspring for generations.

“It’s a provocative finding and it’s well done on so many levels,” says Ken Smith, a biodemographer at the University of Utah in Salt Lake City. But, Smith says, there is ample evidence that having an older father also puts children at greater risk for autism, schizophrenia, some cancers (SN: 3/29/08, p. 200) and other diseases. Some of those diseases may result in part from mutations that accumulate in sperm as a man ages. It is unclear if inheriting longer telomeres can offset the potential downsides of having an aging father or grandfather, he says.

In the new study, the Northwestern researchers studied multigenerational families from the Philippines, measuring the average length of telomeres in more than 2,000 people. A father’s age at birth influenced the length of the children’s telomeres, with older fathers having kids with longer telomeres. Both sons and daughters got the telomere boost from dear old dad, but the long chromosome caps were bequeathed on grandchildren mainly through the paternal line. The data gave a hint that maternal grandfathers influence their grandchildren’s telomere length, but the link didn’t pass statistical muster.

“One of the mysteries of the study is why it doesn’t come from the maternal grandfather,” says Northwestern biological anthropologist Dan Eisenberg.

The team did not study the relationship between telomere length and health. The researchers hope to replicate the findings in other groups of people.

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master’s degree in science journalism from Boston University.

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