Quote:
Originally Posted by ilovetv
I think this is how most of us see longevity as connected to heredity:
ScienceDaily (July 2, 2010) — While environment and family history are factors in healthy aging, genetic variants play a critical and complex role in conferring exceptional longevity, according to a new study by a team of researchers from the Boston University Schools of Public Health and Medicine and the Boston Medical Center.
In a study released July 1 online by the journal Science, the research team identified a group of genetic variants that can predict exceptional longevity in humans with 77 percent accuracy -- a breakthrough in understanding the role of genes in determining human lifespan.
Based upon the hypothesis that exceptionally old individuals are carriers of multiple genetic variants that influence their remarkable survival, the team conducted a genome-wide association study of centenarians. Centenarians are a model of healthy aging, as the onset of disability in these individuals is generally delayed until they are well into their mid-nineties.
Researchers led by Paola Sebastiani, PhD, a professor of biostatistics at the BU School of Public Health and Thomas Perls, MD, MPH, associate professor of medicine at the BU School of Medicine and a geriatrician at Boston Medical Center, built a unique genetic model that includes 150 genetic variants, known as single nucleotide polymorphisms (SNPs). They found that these 150 variants could be used to predict if a person survived to very old ages (late 90s and older) with a high rate of accuracy.
In addition, the team's analysis identified 19 genetic clusters or "genetic signatures" of exceptional longevity that characterized 90 percent of the centenarians studied. The different signatures correlated with differences in the prevalence and age-of-onset of diseases such as dementia and hypertension, and may help identify key subgroups of healthy aging, the authors said.
Notably, the team found that 45 percent of the oldest centenarians -- those 110 years and older -- had a genetic signature with the highest proportion of longevity-associated genetic variants....."
Genetic signatures of human exceptional longevity discovered |
The important thing to remember is that the above study was a "genome-wide association study of centenarians". Genes represent a potential for an outcome, not a certainty. Genes react and respond to the environment within the body and the environment outside the body. If there are genes associated with cancer, for example, they don't represent a certainty that a person will get cancer. Those genes have to be acted upon by the environment. The same applies to almost any disease where there is an association with certain genes. The same rule applies to longevity. Certain genes may be associated with longevity but it's only a potential for an outcome, not a certainty.
That's what twin studies illustrate. Let's say one twin lives to age 85 and the other lives to 100. They both have the same genes so the fact that one lived to age 100 indicates a potential. The other twin wasn't guaranteed the same outcome even though the genes were the same.
And the same rule applies to health. An example was given of twins at age 92. One enjoyed excellent health while the other was in poor health. The one in poor health was nearly blind, suffered incontenence, a broken hip and dememtia. Even though the genes were the same, the healthy twin indicates only a potential for health, not a certainty. If it was a certainty, both twins would have enjoyed the same good health.
If it's not your genes acting alone that determines health and longevity, what's left? It's lifestyle/environment. Genes are being turned on and off all the time, depending on the environment we live in and/or the environment we create for ourselves on a day-to-day basis.