Gene Testing: Predictive Genomics
By JP Saleeby, MD (CMO Zimetry)
Medicine is on the threshold of being able to predict how the environment affects a patient as an “individual.” You can now walk into the doctor’s office, have blood taken or an early morning buccal sampling and within a week find out how the environment around you exposes you or increases your risk for particular diseases. You now have a guide for what you are at risk for, whether it is heart disease, cancer, etc.
Since 2000 when the first draft of the human genome was completed by the Human Genome Project and Celera Corporation we had the raw material in our hands to look into the more than 40,000 genes we have. Today greater than 100,000 single nucleotide polymorphisms (SNPs) have been identified. SNPs are the mutations of a single nucleotide (or base pair) in a gene found in a significant portion of the population. Nucleotides or base pairs are the building blocks of DNA. There are likely to be some 100 times as many SNPs as we have discovered today, and the race is on to find them. These SNPs (or “snips” as they are referred) give variety to our personal “blue print” which we call genetic individuality. Everyone has variations due to point mutations or deletions of one or more nucleotide base pairs and this is where genetic testing can help us “plan” for preventing certain undesirable outcomes when we are exposed to our environment.
There are those gene tests that will show a persons predilection to having higher risks of breast cancer or macular degeneration (where steps can be made to affect outcome) and then there are those that identify genetic diseases such as Huntington’s disease, Tay-Sach’s Disease and Thalassemia to name a few.
In Predictive Genomics, a branch of medicine that identifies polymorphisms in individuals in order to predict and give guidance on treating to prevent disease, we can test for those gene mutations that will respond, to some degree, to lifestyle modification or medication. Genes do not cause disease mind you, but they may predispose us to disease. When the environment and the genes together cause a physical manifestation or observable appearance to an organism it is defined as a phenotype. Some phenotypes we define as disease states, such as coronary artery disease, osteoporosis, or immune deficiency. We cannot as of yet change our genes, so by changing our environment we can enact change on our phenotype.
For example if we find a female patient who tests positive for a bone formation marker (COL1A1) single base pair mutation (polymorphism), then that females phenotype will show aberrant collagen formation that will lead to reduced bone mineral density and increase the risk for osteoporosis. What to do? Higher levels of dietary calcium have been shown to reverse the potentially adverse effects of this SNP. Moderate sunlight exposure or vitamin D supplementation improves calcium absorption in cases like this. And as this woman approached menopause (having this SNP) she would respond very well to estrogen replacement therapy. Not knowing she carried this polymorphism would be a shame (or a crime), since the effects of osteoporosis could be blunted or stopped with proactive preventive medicine. The examples go on and on in predicting risk for cardiovascular disease, inflammatory disease and cancer with selected SNP evaluation.
This tool is new in the arena of healthcare. So new in fact that the technology and its application are only months old. Still considered “experimental research tools” medical insurance does not reimburse for them. This may not be a bad thing, since it offers total confidentiality of results between physician and patient. This information on your genetic blue print may affect your ability to obtain health and life insurance if it falls in the wrong hands. The positive is that now we have a tool in which to check a patient’s individual response to the environment and impact health and wellness with guidance. This will take much of the guesswork out of what recommendations we give and what medications we use. Predictive genomics can actually help a physician determine which drug will work best for a particular disease. You will certainly be hearing more about this new technology soon, as it will change forever how we practice medicine. We can already test for markers for risk for Alzheimers Disease, issues that affect autoimmune disorders, risks for cancer and neurotransmitter production with such tests as ApoE, MTHFR phenotypes, COMT and many many more. All available from Zimetry.
JP Saleeby, MD is medical director of the Carolina Holistic Medicine centers, first to offer Predictive Genomic Testing in Savannah, GA in the early 2000s. He can be reached at email@example.com