How can scientists find genetic differences that may influence the way we age?
They start by studying very large groups of people.
Researchers can compare millions of small differences in DNA across thousands-or sometimes hundreds of thousands-of individuals. They then look for differences that appear more often in people who share a particular characteristic, such as living longer or remaining healthy for longer.
This type of research is called a genome-wide association study, or GWAS.
The name sounds complicated, but the basic idea is simple: look across the DNA of many people and search for patterns.
For example, researchers can ask whether particular genetic differences appear more often in people who live to an advanced age. They can also study lifespan, healthspan or whether someone's parents lived unusually long lives.
GWAS have changed the way scientists investigate the genetics of aging.
Earlier research often started with a particular gene that scientists already suspected might be important.
GWAS allow researchers to look across the entire genome without deciding in advance which genes they expect to find.
And the results have revealed something important.
Rather than discovering one gene that explains why some people live longer, scientists are finding many genetic differences, each usually contributing only a small amount.
When researchers see similar signals repeatedly, they can begin to identify biological processes that may be important for aging-such as cholesterol regulation, inflammation, metabolism and DNA repair.
But finding an association does not mean that a particular genetic difference directly causes longer-or shorter-life.
GWAS provide clues. Scientists then need further research to understand what those clues actually mean biologically.
