Nutrigenomic testing and the methylation pathway

Townsend Letter for Doctors and Patients,  Jan, 2006  by Amy Yasko,  Garry Gordon

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Many factors influence susceptibility to disease. These include an individual's stress load, environmental toxins, the exposure to infectious agents, as well as underlying genetic susceptibility to these diseases. The precise combination of components that interact to cause multifactorial diseases may be different in every individual. There may be slight or enormous changes in the relative contributions of each of these factors to disease. (1) Multifactorial diseases are caused by infections and environmental events occurring in genetically susceptible individuals. Basic parameters like age and gender, along with other genetic and environmental factors, play a role in the onset of these diseases. Infections combined with excessive environmental burdens only lead to disease if they occur in individuals with the appropriate genetic susceptibility. (2)

One clear, definitive way to evaluate the genetic contribution of multifactorial disease is to take advantage of new methodologies that allow for personalized genetic screening. Genetic testing enables individuals to evaluate and address the genetic component of multifactorial disease. (3) Currently, tests are available to identify a number of underlying genetic susceptibilities based on allelic variations that are found in the DNA. Unfortunately, the use of this testing has fallen short of expectations. Perceived impediments to the use of genetic screening to identify underlying susceptibilities to disease include concerns of job discrimination, loss of insurance coverage and the inability to address diagnosed disease states. While 79% of Americans surveyed responded that they would take a genetic test to assess the risks of inherited diseases, and 41% said they had a family history of genetic or inherited health problems, the reality is that genetic testing is severely underutilized. (4) Genetic screening should be the wave of the future for both alternative healthcare as well as allopathic medicine. Both disciplines (alternative and allopathic Medicine) should be taking advantage of the strides made in the Human Genome Project that allow simple genetic tests to look at genetic weaknesses. (5-7)

The goal of the Human Genome Project was to identify all the approximately 30,000 genes in human DNA and to determine the sequences or "spelling" of the 3 billion chemical base pairs that make up human DNA. This project was completed in June of 2000. As a direct consequence of having the complete sequence of the human genome, research first focused on identifying particular genes that were involved with specific diseases. The next step has been to use this information to look for the presence of these identified disease causing genes in an individual person. Rather than looking at complete gene profiles, it is also possible to look at particular changes in the "spelling" of DNA in only specific areas of interest. In this way, it is possible to quickly get a sense of known genetic weaknesses. In order to find relationships between genetic changes and the susceptibility to disease, this testing is done utilizing single nucleotide polymorphisms, otherwise known as SNPs (pronounced snips). This process systematically compares genomes of those individuals with a disease or an imbalance in a nutritional pathway to the corresponding DNA of a "normal" population.

The lack of use of this powerful diagnostic technology highlights the need for adequate means to address the results of personalized genetic testing. It is a travesty to have the ability to specifically identify genetic weakness, yet have this technology underutilized out of fear. It points to a dire need for therapeutic technologies that take advantage of this same genetic information with an eye toward personalized treatment or nutritional supplementation, rather than simply personalized diagnosis. It is essential to take advantage of the strides that have been made in the human genome project not only to understand underlying genetic susceptibilities but also to successfully deal with chronic health issues. (8)

The beauty of nutrigenomic testing is that it focuses on weaknesses in known, characterized nutritional pathways. Knowledge of these pathways lends itself to providing nutritional "bypasses" for genetic mutations. Nutrigenomics integrates concepts in molecular biology and genomics to study the ability of foods and nutritional supplements to interact with genes to influence health and lower the genetic risk component for multifactorial disease. (9) This field of nutrigenomics is perhaps best described by the group that is dedicated to promoting this new science of nutritional genomics. According to the National Center of Excellence in Nutritional Genomics at UC Davis, "The science of nutrigenomics seeks to provide a molecular understanding for how common dietary chemicals (i.e., nutrition) affect health by altering the expression and/or structure of an individual's genetic makeup. Just as pharmacogenomics has led to the concept of "personalized medicine" and "designer drugs," so will the new field of nutrigenomics open the way for "personalized nutrition." In other words, by understanding our nutritional needs, our nutritional status, and our genotype, nutrigenomics should enable individuals to manage better their health and well-being by precisely matching their diets with their unique genetic makeup."