Researchers have linked a shorter lifespan with two common gene changes. One copy of either of these two changes to DNA (called variants) could shave a year off your life expectancy. People who inherit two copies – one from mom and one from dad – of both variants could expect to lose about 3.3 to 3.7 years. The findings were published in Nature Communications this week. 

Genetic factors account for up to 25 percent of the variation in longevity, previous studies have suggested. But research into the biological basis of human lifespan has been limited by our relatively long lives: Waiting for study participates to die may take decades. 

So, a team led by University of Edinburgh’s James Wilson came up with a novel approach: regressing parental lifespans. "You compare the parent trait to the offspring genes," Wilson explains to IFLScience. "Because we share half our genomes with our parents, we can use our genomes to represent theirs and so carry out an association study with the parental lifespan and the offspring genome." They turned to data from the U.K. Biobank (UKB) study, which has made available genomic information from 152,732 volunteers aged 40 through 69 at the beginning of the long-term study. The ages of their parents and whether they were alive or not at the time were reported in the UKB questionnaire. 

The researchers found common variants near APOE and CHRNA3/5 genes to be associated with lifespan. "Two gene variants explain about three and a half years of lifespan!" Wilson says. 

APOE has been linked to Alzheimer's dementia, high cholesterol, and coronary disease risk. Meanwhile, the CHRNA3/5 gene cluster is associated with an increased risk of lung cancer, nicotine dependence, and respiratory problems in smokers. 

These variants are pretty common in the population: More than two-thirds of us will inherit a single copy of one of these DNA changes. And three in 1,000 people will inherit two copies of both variants. Furthermore, these variants have age- and sex-related effects on lifespan. The variant linked to Alzheimer's has a greater impact on older women, while the variation associated with lung disease influences middle-aged men more.

"Although the effect of these genetic variants on lifespan is surprisingly large, it is important to remember that this is only part of the story," study co-author Peter Joshi from the University of Edinburgh said in a statement. "Lifestyle has the greatest impact on how long we live and that is under our control."