Genes-R-Us — Genomics secrets to longevity and New Year’s resolutions
Posted: Wednesday, January 4, 2012 5:04 pm
Longevity coupled with good health. Isn’t that what we all want? I certainly am not interested in a long life without my mental faculties or with such poor health that I end my days in a nursing home.
Last week I attended a memorial service that was truly a celebration of a L-O-N-G life well-lived. The woman, who lived almost 98 years, had been remarkably healthy during her life, save an episode of breast cancer which she minimized if she ever spoke of it. She possessed keen mental faculties to the end and truly did not look her age.
Can genomics tell us anything about the secrets of a long life?
In the summer of 2010 there was much hoopla over a paper published in a prestigious peer-reviewed journal entitled “Genetic Signatures of Exceptional Longevity in Humans.” The 150 SNPs were said to help predict one’s chance of living to be 100.
SNPs are those single point variations in our DNA that vary between our genomes in known and simple ways. The Direct-to-Consumer (DTC) testing Internet sites were abuzz with “do-it-yourselfers” checking to see which of the 150 SNPs were on their testing platform and if they had the “good” versions of the SNPs.
Unfortunately, within days of publication many legitimate objections were raised about the analysis used in the “Genetic Signature” paper. (Hey, ya gotta get the math right!) It was fully retracted one year later by the authors and the data are now being reanalyzed.
In a different paper, published about the same time as the other paper was formally retracted, structural variations (SV) were said to account for far more of the variation between human genomes than SNPs. This paper challenged scientist to look deeper than SNPs, and rightly so.
An SV is said to occur when contiguous swaths of DNA “letters” are either deleted, inserted, copied multiple times and then inserted, or flipped 180 degrees between genomes. An SNP is a single letter change between genomes.
It is much more costly, 100 to 1,000 times more so, to get SV information — typically one has to have their whole genome sequenced. DTC genetic testing gives you a subset of your SNPs-1.5 million of them currently. DTC genetic testing does not yet exist for your SVs.
All caveats aside, there are several highly validated SNPs that are associated with longevity. Unfortunately these SNPs explain so little of the variability in centenarians that they are not predictive of longevity.
In other words, it is hardly worth the effort to find the values for this handful of SNPs other than to satisfy one’s intellectual curiosity.
Moreover, we know that how our genes express themselves is very much tied to our environmental exposure and behavioral habits. Epigenetics is the study of this gene/environment relationship.
Epigenetics has demonstrated the power of New Year’s resolutions — including eating healthy, exercising and giving up smoking — to silence bad genes and turn off good genes.
My adoptive paternal grandmother lived to be 104 years old. She lived with our family during most of my childhood. For many years during the holidays, Granny and I unwrapped and re-wrapped every single gift under our tree well before Christmas day. She was the lookout and I was the “hands.”
Granny would have been in her late 80s when I was about 10 years old (and having way too much fun with the Christmas gifts). She laughed more than anyone else in my childhood … way more. She was able to see the humorous side to even her own “bad” luck, which was often the source of nicknames she gave to herself.
Several months ago I asked my recently deceased friend what she thought the secret was to her almost 98 years of youthful life. She considered the question thoughtfully and then responded in her southern-comforting voice, “I think that the secret is love of the Lord.”
As the technology for whole genome sequencing becomes more affordable, scientists will begin to understand the genomics of longevity. In the meantime, and for 2012 in particular, may you have much laughter in your life and experience the joy of loving the Lord.
Editor’s note: Nancy Miller Latimer has worked in scientific research and development for 27 years. She blogs at neuronalbeauty.blogspot.com. Published in The Messenger 1.4.12