BERKELEY, Calif. — After 50, your risk of disease is determined more by your age and the environment than by the genes you inherit from your parents, a new study reveals.
Once humans hit a certain age, our individual DNA differences have far less of an impact on whether we’re prone to age-related diseases like cancer, dementia, or diabetes. Our personal genetic makeup is still very useful in determining health risks at a young age, UC Berkeley researchers say, but risks among older people are tied to their age and environmental factors. The process of how people age even deviates among identical twins over 55 who have the exact same genes.
The study finds disease risk of someone over 50 is tied more to their older age or the water they drink or the air they breathe than by their family DNA.
“There’s been a huge amount of work done in human genetics to understand how genes are turned on and off by human genetic variation,” says Peter Sudmant, a UC Berkeley assistant professor of integrative biology and member of the Center for Computational Biology, in a university release. “But our project came about by asking, ‘How is that influenced by an individual’s age?’ And the first result we found was that your genetics actually matter less the older you get.”
The Berkeley study findings appear to fall in line with Brazilian biologist Peter Medawar’s benchmark hypothesis which contends that genetic history is only important when discussing the health susceptibilities of young people, not old people.
‘Almost all human common diseases are diseases of aging’
The gene variations you receive from your respective sperm and egg donor parents are more closely tied to evolution: those characteristics helped to ensure that you survived long enough to reproduce. However, once humans pass a certain age, the Berkeley researchers say the genes you inherited matter less and less.
“Almost all human common diseases are diseases of aging: Alzheimer’s, cancers, heart disease, diabetes. All of these diseases increase their prevalence with age,” Sudmant continues. “What our study is showing is that, well, actually, as you get older, genes kind of matter less for your gene expression. And so, perhaps, we need to be mindful of that when we’re trying to identify the causes of these diseases of aging.”
The study authors assessed the impact of genetics and aging on 27 different human tissues collected from 1,000 individuals. They found the impact of aging on the tissues varies 20 times more than the relative role of genetics. The researchers say that human tissues and even people’s blood are always regenerating and must still “turn on” later in life to survive. As people get older, however, those genes become more susceptible to cancerous mutations.
“From an evolutionary perspective, it is counterintuitive that these genes should be getting turned on, until you take a close look at these tissues,” Sudmant says.
“These five tissues happen to be the ones that constantly turn over throughout our lifespan and also produce the most cancers. Every time these tissues replace themselves, they risk creating a genetic mutation that can lead to disease.”
The newly published study, in a journal Nature Communications, suggests that drug researchers and predictive health professionals should focus less on people’s genetic variants and more on age and environment.
personal genetic makeup is still very useful in determining health risks at a young age, UC Berkeley researchers say, but risks among older people are tied to their age and environmental factors