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Introduction
Genomics and health
Pharmacogenomics
The World Health Organization has defined pharmacogenomics as the study of DNA sequence variation as it relates to differential drug response in individuals, i.e., the use of genomics to determine an individual’s response. Pharmacogenomics refers to the use of DNA-based genotyping in order to target pharmaceutical agents to specific patient populations in the design of drugs [9][15].
Current estimates state that 2 million hospital patients are affected by adverse drug reactions every year and adverse drug events are the fourth leading cause of death. These adverse drug reactions result in an estimated economic cost of $136 billion per year. Polymorphisms (genetic variations) in individuals effect drug metabolism and therefore an individual's response to a medication. Examples of ways in which genetics may affect an individual’s response to drugs include: drug transporters, metabolism and drug interactions. Pharmacogenetics may be used in the near future by public health practitioners to determine the best candidates for certain drugs, thereby reducing much of the guesswork in prescribing drugs. Such actions have the potential to improve the effectiveness of treatments and reduce adverse drug events [10].
Nutrition and health
Nutrition is very important in determining various states of health. The field of nutrigenomics based on the idea that everything ingested into a person’s body affect the genome of the individual. This may be through either upregulating or downregulating the expression of certain genes or by a number of other methods. While the field is quite young there are a number of companies that market directly to the public and promote the issue under the guise of public health. Yet many of these companies claim to benefit the consumer, the tests performed are either not applicable or often result in common sense recommendations. Such companies promote public distrust towards future medical tests that may test more appropriate and applicable agents.
An example of the role of nutrition would be the methylation pathway involving methylene tetrahydrofolate reductase (MTHFR). An individual with the gene variant or SNP (single nucleotide polymorphism) may need increased intake of B
12 and Folinic acid to override the effect of a variant SNP. Increased risk for neural tube defects (http://www.blackwell-synergy.com/doi/pdf/10.1046/j.1469-1809.2003.00027.x) and elevated homocysteine levels have been associated with the MTHFR C677T polymorphism.(http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=11953142&dopt=Abstract
In 2002, researchers from the Johns Hopkins Bloomberg School of Public Health identified the blueprint of genes and enzymes in the body that enable sulforaphane, a compound found in broccoli and other vegetables, to prevent cancer and remove toxins from cells. The discovery was made using a “gene chip,” which allows researchers to monitor the complex interactions of thousands of proteins on a whole genome rather than one at time. This study was the first gene profiling analysis of a cancer-preventing agent using this approach [11] [13]. University of Minnesota researcher Sabrina Peterson, PhD, RD, coauthored a study with Johanna Lampe of the Fred Hutchinson Cancer Research Center, Seattle, in October 2002 that investigated the chemoprotective effect of cruciferous vegetables (e.g., broccoli, Brussels sprouts). Study results published in The Journal of Nutrition outline the metabolism and mechanisms of action of cruciferous vegetable constituents, discusses human studies testing effects of cruciferous vegetables on biotransformation systems and summarizes the epidemiologic and experimental evidence for an effect of genetic polymorphisms (genetic variations) in these enzymes on response to cruciferous vegetable intake [12][14].
Healthcare and genomics
How will obtaining my genetic blueprint benefit me? Why find that I am more susceptible to getting a disease that has no cure? These are relevant questions that are continually being asked by the public, as researchers continue to unfold the mystery of the human genome. It is important to ask these questions taking into consideration the current knowledge of genomics, in comparison to, the potential genomics will one day have on healthcare as we know it today.
Researchers have found that almost all disorders and diseases that affect humans reflect the interplay between the environment and theirgenes; however we are still in the initial stages of understanding the specific role genes play on common disorders and diseases.[11] For example, while news reports may give a different impression, most cancer is NOT inherited. It is therefore likely that the recent rise in the rates of cancer worldwide can be at least partially attributed to the rise in the number of synthetic and otherwise toxic compounds found in our society today. Thus, in the near future, public health genomics, and more specifically environmental health, will become an important part of the future healthcare-related issues.
Potential benefits of uncovering the human genome will be focused more on identifying causes of disease and less on treating disease, through: improved diagnostic methods, earlier detection of a predisposing genetic variation, pharmacogenomics and gene therapy.[13]
For each individual, the experience of discovering and knowing their genetic make-up will be different. For some individuals, they will be given the assurance of not obtaining a disease, as a result of familial genes, in which their family has a strong history and some will be able to seek out better medicines or therapies for a disease they already have. Others will find they are more susceptible to a disease that has no cure. Though this information maybe painful, it will give them the opportunity to prevent or delay the on-set of that disease through: increased education of the disease, making lifestyle changes, finding preventive therapies or identifying environmental triggers of the disease. As we continue to have advances in the study of human genetics, we hope to one day incorporate it into the day-to-day practice of healthcare. Understanding one's own genetic blueprint can empower oneself to take an active role in promoting their own health.[14]
Genomics and understanding of disease susceptibility can help validate family history tool for use by practitioners and the public. IOM is validating the family history tool for six common chronic diseases (breast, ovarian, colorectal cancer, diabetes, heart disease, stroke) (IOM Initiative). Validating cost effective tools can help restore importance of basic medical practices (e.g. family history) in comparission to technology intensive investigations. (http://www.cdc.gov/genomics/about/reports/2005/letter.htm)