June 12, 2012 12:36 pm

Kids of older fathers, grandfathers may live longer, healthier lives: study

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TORONTO – Children of older fathers and grandfathers may receive life-extending benefits, according to new research.

A study led by Northwestern University’s Dan Eisenberg looked at telomere length in 2,023 children. Telomeres are DNA found at the end of the chromosomes in all cells in the human body, and they protect the DNA.

“The common analogy that’s used is to think of them in terms of those little plastic tips on the end of your shoelaces that make your shoelaces work and keep them from fraying,” says Eisenberg, a doctoral candidate in anthropology. “There seems to be an analogous role for these telomere sequences.”

Each time a cell divides to replicate and make more cells, the DNA also divides, and tends to get a bit shorter in the process. This is especially pronounced where the telomere sequence is, so telomeres tend to get shorter with age.

However, one exception where telomeres actually get longer with age is in sperm samples. As a result, the offspring of older fathers tend to have longer telomeres.

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This study took place in the Philippines and spanned almost 30 years. Researchers measured telomere lengths that were gathered from a blood sample in 2005, and looked at how the date of birth of the father and the grandfather related to the telomere length of the children.

Eisenberg explains the link between father and child has already been shown in past research, but that the new contribution of his study is that this effect persists across another generation.

“So we’ve looked at the age that the grandfather had his children at, and the telomere length of the grandkid. And we showed that for paternal grandfather being older at the birth of the father predicts the grandchildren will have longer telomeres.”

The researchers do not categorize “older” fathers with a specific age range. Instead, Eisenberg explains that the telomere lengthening appears gradual, without a certain point where the length starts to increase or decrease.

“It just seems to be pretty stable that for every year older the man is, the telomere lengths in his sperm are getting (on average) the same little bit longer,” says Eisenberg.

So why is this new finding significant?

Shorter telomere length has been shown to be associated with poorer health in past studies, so Eisenberg says one implication is that people who had older fathers and older grandfathers might have better health and longevity.

“Things like immune function, the immune system, are probably influenced…and then it’s also implicated in cardiovascular disease as well,” says Eisenberg.

“And in some studies it’s been shown that people who have shorter blood telomere length tend to have increased rates of mortality, and the substantial portion of that mortality comes from infectious diseases, which is consistent with [telomeres’ relation to immune system].”

While Eisenberg says his study is intriguing in that it is contrary to past research that associates older fathers with negative health outcomes, he suggests further research is needed to explore the net effect of differences in father’s age.

“We’re not making any sort of recommendation that people delay having children because of something like this,” he says.

Next steps for research include looking at more distant ancestors, and exploring whether factors aside from age change the telomere length of men’s sperm, as well as any potential effects on the length of their children’s lives. 

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