Genetic Testing: SNPs
Chester J. Zelasko, Ph.D. | October 11, 2006

The Human Genome Project was a 13-year effort completed in 2003 to map our genetic code (1). While the sequencing of our DNA is complete, the identification of all the genes and mutations of those genes continues. Thousands of scientists all over the world are working on the project with the goal of improving the health of all people through medications, nutrition, and other environmental factors.

Regular readers of the Newsletter have had questions about genetic testing. What is genetic testing? What is actually tested? And most important, what does it mean? We’ll tackle more advanced concepts in future newsletters, but today let’s start with the basics.

DNA 101
DNA is made up of repeating sequences of only four molecules called bases: adenine (A), thymine (T), guanine (G), and cytosine (C). These bases form weak bonds between each other (A-T or G-C). These weak bonds hold the double strand of DNA together--good thing, too, because your DNA is over three billion paired-bases long.

How much is three billion? Start counting one number per second beginning at 1 until you reach 3,000,000,000--if you never sleep and never take time off, you’ll be at it for about 95 years! It’s no wonder that even with high-speed computers, it took 13 years to sequence the entire genetic code.

DNA is broken into smaller pieces called chromosomes. Human beings have 24 chromosomes that can be between 50 and 250 million base-pairs long. Each chromosome contains smaller pieces of DNA called genes. The purpose of most genes hasn’t been identified yet, but we know that each gene has a distinct role in the body and it all begins by making proteins. The proteins made by each gene can communicate with other parts in the cell and with other cells and organs in the body.

Understanding what turns the genes on may turn medicine on its ear in the future. Instead of insulin shots, diabetics will get DNA-repair mechanisms to stimulate pancreatic cells to start producing insulin again; people with osteoporosis will get DNA-repair mechanisms to help bones start laying down bone mineral again. That’s many years away, but it seems obvious that’s where science is heading.

Single Nucleotide Polymorphisms (SNPs)
When something is three billion pieces long, it’s understandable that’s scientists have difficulty finding where mistakes may have occurred. Using individual genes reduces that to the millions. When just one mistake occurs in a single base-pair in a gene, that’s called a Single Nucleotide Polymorphism or SNP, pronounced “snip.” Commercially available genetic testing uses SNPs to identify mutations in the tested person’s genes. Those with mutations can potentially be at risk for diseases such as osteoporosis, heart disease, and cancer.

But what does a genetic test for a specific gene actually do and what does it mean? Let’s use one of these SNPs to explain--Superoxide Dismutase 2. Instead of using the entire name of a gene, scientists have developed a sort of shorthand, and for this one it’s SOD2; the 2 means that there’s more than one form of the SOD gene.

Each genetic test examines a specific location on the gene to see if a mutation occurs. For SOD2, the test examines position 47 along the base-pairs. If a G is located there, the gene is normal. However, is a C has been substituted for the G, that’s a mutation; it would indicate your genotype or what’s in your specific genetic code.

SOD2 is a gene that produces a protein that helps quench the superoxide ion. Think of the superoxide ion as an oxygen molecule gone crazy--SOD2 fixes it. However, with a mutated form of the gene, the process may not work as well. Fortunately, there are other forms of SOD to deal with the superoxide ion.

Then what?
What does having a mutation mean? It would be easy if it meant that you’d get a specific form of cancer or other disease, but it isn’t that straightforward. What it means is that your risk of developing a particular disease is a little higher.

Fortunately, there are many things you can do about this and other SNPs you get tested for. You can compensate for your genetic shortcomings by eating more fruits and vegetables, reducing exposure to toxins such as cigarettes and exhaust fumes, taking antioxidants such as vitamin E, C, and the mineral selenium, and taking a supplement with phytonutrients.

Of course, one option would be to just do those things and skip the genetic test. This is just the beginning of genetic testing, and as more is discovered about the interaction of SNPs and the environment, more specificity about what to do to cope with a particular mutation will be discovered as well. More than just the general recommendations of today, scientists will be able to recommend specific foods or supplements that may help more precisely. But your genes can’t change, so getting tested now is a good idea--you’ll know what to watch for and be able to take advantage quickly of new discoveries.

Whether you’re tested or not, remember that you can affect the way your genes behave by adopting a healthier lifestyle. That’s the better life way.

If you want to know more about genes and genetic testing, purchase a copy of “It’s Not Just Your Genes” available exclusively from Better Life.

  1. This weblink takes you to the Genome Project Home Page. There are resources applicable to every age and educational background, so check it out.
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