A new study has identified gene variations that determine life expectancy.
In the United States, life expectancy is currently averaged at 78.8 years, according to data from the Centers for Disease Control and Prevention (CDC). They also identify the leading causes of death, naming heart disease, cancer, and chronic respiratory diseases as some of the main culprits.
Scientists have previously looked at our genetic makeup for clues that indicate how long each person is likely to live. However, until now, only two genes had been identified as linked with longevity (defined as living beyond age 85) in humans.
A new study led by Prof. Zoltán Kutalik - from the Institute of Social and Preventive Medicine and the Swiss Institute of Bioinformatics, both in Lausanne, Switzerland - has now identified a total of 16 genetic markers that dictate how long a person will live. Of these, 14 are completely new discoveries.
The findings were published this week in the journal Nature Communications.
Three genes linked with longevity
Prof. Kutalik and his colleagues analyzed data collected from 116,279 people, and investigated 2.3 million single-nucleotide polymorphisms (SNPs), which are genetic variations that can reveal whether or not an individual is predisposed to a particular illness or condition.
According to the researchers, around 1 in 10 people have a combination of genetic markers that determine a shorter lifespan than average. They explain that inheriting a variation indicative of a diminished life expectancy may mean shortening life by up to 7 months.
The study found that SNPs impact an individual's lifespan by linking to several factors of disease or addiction risk, thus making it likely that a person who is predisposed to a particular health condition might also be susceptible to dependence on a substance, such as nicotine.
In addition to the identification of the 14 new SNPs, data on gene expression led to the discovery that a low expression of three genes associated with the SNPs in the brain - RBM6, SULTA1, and CHRNA5 - determines a prolonged lifespan.
This finding is compatible with previous research indicating that CHRNA5 is linked with nicotine addiction leading to lung cancer, so it makes sense that a low expression of the encoding gene would be more beneficial.
Human and animal models compatible
Study collaborator Prof. Johan Auwerx, from the Ecole Polytechnique Fédérale de Lausanne in Switzerland, explains that to test whether these genes could cause longevity, the team performed additional experiments on mice.
The researchers found that mice with a low expression of the RBM6 gene in the brain lived much longer than their counterparts.
"Interestingly, the gene expression impact of some of these SNPs in humans is analogous to the consequence of a low-calorie diet in mice, which is known to have positive effects on lifespan."
Prof. Marc Robinson-Rechavi, Swiss Institute of Bioinformatics and the University of Lausanne
The researchers also showed interest in the parallels between molecular mechanisms in human and animal models, and they expressed a wish to continue exploring these similarities.
In addition to these discoveries, the study also promotes the use of a new and more efficient computational framework in the context of genetics and bioinformatics. Prof. Kutalik and his colleagues suggest that this framework could have more wide-reaching uses in precision medicine.