Genetic testing for preventive medicine

February 26, 2012

Environment, Health Concerns

More than 99 percent of human DNA sequences are exactly the same with every person. Variations in the remaining 1 percent or so can have a major impact on how any of us will respond to disease.

by Dr. Martha Grout — 

By decoding some 40,000 genes in the human body, the Human Genome Project opened up an entirely new spectrum of knowledge. Genetic testing now gives us the ability to understand the body’s vulnerabilities and each person’s unique genetic predispositions.

Genetic testing can sample the risk for about 1,500 diseases. Having a genetic marker for a disease is not a guarantee that you will absolutely get that disease — with very few exceptions, such as Huntington’s disease, muscular dystrophy, Tay-Sachs and cystic fibrosis. About 15 years ago, the variant (or mutant) genes BRCA1 and BRCA2 were found to predispose women to breast and ovarian cancers. The gene variant NAT2 may predispose some individuals to colon cancer. But not everyone with these gene variants gets cancer. Why is this?

Environmental factors can turn genes on and off. Science is finding that the interplay of environmental toxicology and genetics makes us who we are and often determines whether we are healthy or sick. Most diseases are due to a combination of genetic and environmental factors. Sometimes genetics are the stronger factor, but more often than not, environmental influences are stronger.

More than 99 percent of human DNA sequences are exactly the same with every person. Variations in the remaining 1 percent or so can have a major impact on how any of us responds to disease. Genetic disease results from a variation, or mutation, in a chromosome or in one or several base pairs on a gene. Some mutations are inherited, but most occur spontaneously.

For many of the adult-onset diseases, genetic mutations can occur over the lifetime of the individual while the cells are making copies of themselves or dividing. Environmental effects such as radiation, chemicals and lack of nutrient-dense food play a role in these mutations.

Kári Stefánsson, the famous gene hunter who led the effort that mapped 65 percent of Iceland’s genome, said, “There’s a paradigm shift from intervention to preventive medicine as we speak. It happened when people started to download information about diseases.” People increasingly are looking for answers that mainstream medicine rarely provides, which is how to prevent disease.

You can acquire some very useful information through genetic testing. For example, do you have the genes to efficiently use folic acid? If not, you can experience complications in pregnancy, be more susceptible to autism and be  prone to elevated levels of homocysteine in your blood, which can lead to heart attacks, strokes, depression, cervical and uterine cancer, arthritis, spina bifida and Alzheimer’s.

Interaction between vitamin D and another common genetic variant, DRB1*1501, alters the risk of developing multiple sclerosis (MS). In 2009, researchers found that if too little of the vitamin is available, the gene may not function properly and the person is more likely to develop MS.

Knowing from a genetic test that you are at risk allows you to pay closer attention to the warning signs, detect diseases earlier and very possibly head off the worst case scenarios from that risk.

 

Martha Grout, M.D., M.D.(H), specializes in the reversal of chronic disease and makes use of genetic testing. She can be reached at the Arizona Center for Advanced Medicine, 480-240-2600, www.ArizonaAdvancedMedicine.com.

Reprinted from AzNetNews, Volume 29, Number 3, June/July 2010.

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