Dubious Genetic Testers
by Stephen Barrett and Harriet Hall
During the past few years, several companies have begun offering genetic testing, combined with guidance on diet, supplement strategies, lifestyle changes, and/or drug usage. These companies claim that the results of their genetic tests can be used to improve health outcomes. This article explains why such testing should be avoided.
Until recently, hereditary tendencies were determined mainly by examining the family history of the individuals involved. Monogenic disorders like cystic fibrosis, neurofibromatosis, Huntington’s disease, myotonic dystrophy, and others have direct correlations between a certain gene and the onset of a disease. Within the past decade, however, genes have been identified that contribute to Alzheimer's disease, amyotrophic lateral sclerosis (Lou Gehrig’s disease), familial colon cancer, and many other conditions, though the relationship between afflicted people and their genotypes are less clear. Many laboratories and clinics provide genetic testing and counseling, and scientific research in this field is progressing very rapidly.
Genetic tests analyze human DNA, RNA, chromosomes, proteins, or certain metabolites in order to detect alterations related to a heritable disorder. Tests that identify carriers of various diseases can be used to help couples decide whether or not to have biological children. Scientists hope that further research will lead to strategies for preventing or treating hereditary diseases. Genetic tests can also help diagnose inherited diseases related to problems with a single gene and lead to earlier treatment. At present, however, only a few such strategies are known, and none justify the commercial activities described in this article.
Many of the tests being marketed directly to consumers are for common gene variations that have been linked to major illnesses, such as coronary heart disease. These diseases have hereditary aspects but are heavily influenced by lifestyle and environmental factors. For such diseases, genetic testing can indicate that an individual is more susceptible than most people, but it cannot predict with certainty that the disease will develop.[1] For these reasons, the screening tests described in this article are not recommended by any authority and are not FDA-approved as a basis for recommending treatment of any kind.
Great Smokies Diagnostic Laboratory’s Genovations™ Test
Great Smokies Diagnostic Laboratory (GSDL) of Asheville, North Carolina, claims that its Genovations test line “empowers physicians and patients to realize earlier, more effective preventive interventions — years before disease develops; precise, customized therapies that truly address each individual’s needs and improved clinical insight into patients with treatment-resistant ‘chronic’ conditions.”[2] Genovations testing is one of many questionable tests that GSDL offers through “holistic physicians,” chiropractors, and other non-traditional practitioners or directly to the public. According to the Genovations Web site, “Genovations™ tests measure individual genetic variations, called single nucleotide polymorphisms (SNPs) that, under the influence of environmental triggers, can make even a healthy person more prone to develop certain diseases or physiological imbalances.”[3]
The tests currently offered include: CardioGenomic Profile (to identify SNPs associated with cardiovascular disease), OsteoGenomic Profile (to identify SNPs associated with osteoporosis), DetoxiGenomic Profile (to identify SNPs associated with “detoxification defects” supposedly related to increased risk for certain cancers, chronic fatigue syndrome, multiple chemical sensitivity, and alcoholism), and ImmunoGenomic Profile (to identify SNPs associated with immune system defects, asthma, atopy, osteopenia, heart disease, and infectious diseases).[4] The Genovations Web site further states:
Are you plagued by a chronic condition that resists medical treatment? Testing can reveal whether you have genetic variations that make you more vulnerable to the harmful effects of toxins. Or if you are less likely to respond well to certain drugs or nutrients.
Do you have a family history of a condition like heart disease or osteoporosis? When conditions “run in families” they often have a genetic component. Testing can show what specific genetic factors could pose a potential problem for you.
Based on your genetic test results, your health care practitioner can work with you to develop a customized treatment plan. But the support doesn’t stop there. Testing is also available that can monitor whether your personal healthcare strategy is having a positive impact on your genetic risks.[5]
The above quotations clearly promise more than Genovations can deliver. In order for a test to be cost-effective, it has to provide information that is not available elsewhere and that can steer the patient toward beneficial treatment. No studies have shown that genetic testing is as good as a simple family history or ordinary laboratory tests for determining what people should do to prevent osteoporosis or cardiovascular disease. The idea that people who have “chronic conditions” are likely to benefit from genetic testing is preposterous. No studies have demonstrated that nutrient formulas based on genetic testing are as good as standard medical treatment based on appropriate diagnostic testing or that GSDL’s nonstandard “functional assessments” are valid.
Most of the conditions related to Genovations testing are either poorly understood (such as chronic fatigue syndrome) or are known to have many contributing factors (such as coronary heart disease). Many different genes are involved, often on different chromosomes, and the expression of the genes is affected by environmental factors. Genetic variants may well influence the development of common diseases, but it is far too early to be guessing what variants affect what disease, much less to be recommending treatment in the form of diet and supplements.
GeneLink, NuGenix and Garden State Nutritionals
GeneLink, NuGenix, and Garden State Nutritionals have teamed up to market genetic tests accompanied by supplement recommendations. GeneLink, headquartered in Margate, New Jersey, provides the genetic tests. Its reports to the Securities and Exchange Commission state that it was formed “to offer to the public the safe collection and preservation of a family’s DNA material for later use by the family to determine genetic linkage, but a recent press release describes it as “a leader of genetic assessments direct-to-consumer,” which is a very different purpose.[6,7] The company’s Web site states:
No longer will people be forced to speculate, guess or use trial and error to determine which nutritional supplements or skin-care products are best for them. For the first time, by simply swabbing the inside of [the] mouth (using GeneLink’s Patented Collection Kit) and sending the collected sample to GeneLink’s laboratories…people can be directed to personalized products - specifically formulated to help compensate for predicted deficiencies.[8]
Garden State Nutritionals, a custom manufacturer in West Caldwell, New Jersey, supplies the supplement products. NuGenix, of Berwyn, Pennsylvania, is operated by the children of GeneLink’s president. Its “medical advisor” is Alan H. Pressman, a chiropractor who for many years has hosted a supplement-promoting radio talk show called “Healthline” and has marketed his own line of supplements.
In December 2002, NuGenix’s “genetic profiling kit” plus a month’s supply of the “Bodygenix Nutrition Regimen” cost $299.95, plus shipping and handling. The regimen is said to be focused on seven formulas: “Multi-Base Formula” (a multivitamin with additional ingredients that “protect and support the antioxidant and detoxification systems”), “Oxidative Stress Supplement 1” (to “benefit mitochondrial function”), “Oxidative Stress Supplement 2” (to “help detoxify the body”), “Detoxification Supplement 1” (to “support optimal function of detox systems”), “Heart and Circulatory 1” (to help lower homocysteine and cholesterol levels) “Heart and Circulatory 2” (also to help lower homocysteine levels), and Immune Health Supplement 1 (to help “balance certain aspects of immunity”).
The Web site doesn’t indicate how the test results influence the composition of the supplement products the customers receive. But the descriptions of the ingredients make it clear that the make-up of the final product is likely to be irrational. For example, the site correctly notes that high levels of the amino acid homocysteine may be an important factor in causing coronary heart disease and that lowering homocysteine levels may be beneficial. But the correct way to deal with this is to measure blood levels and take the amounts of B-vitamins that can normalize high levels.[9] Genetic testing contributes nothing to this process. Similarly, the correct way to deal with abnormal cholesterol levels is to measure them by means of blood tests and use lifestyle changes and approved drugs to correct them.
Seryx’s Signature Genetics™
Seryx, which is based in Montreal, Canada and Cherry Hill, New Jersey, invites patients to use its Signature Genetics service to “discover how your genes hold the secret to your well-being.”10 The service, which is available by annual subscription, must be obtained from a doctor who has been trained by the company. The company promises — based on a genetic blood test and answers to a detailed questionnaire — “detailed, individualized, practical recommendations on nutrition, lifestyle, and medications — with actions you can take immediately to improve your well-being and uncover your optimal health.” To obtain the service, patients must purchase a membership and pay an annual fee that entitles them to notification when new discoveries pertain to their genetic profile. The Web site offers physicians a “significant practice-building opportunity,” but it offers no objective evidence that such practice-building will benefit patients. According to a company spokesperson, the cost of the service depends on how many test “modules” the doctor recommends after interpreting the patient’s information. Patients then pay the doctor directly, with a minimum charge of $500.
The effectiveness and toxicity of most medications can vary considerably from patient to patient and for many medications these individual differences are partly due to variations in the genes related to drug-metabolizing enzymes, drug transporters, and/or drug targets.[11] For example, someone who metabolizes a drug more slowly than someone else may respond to the drug at a lower dose and be more likely to develop unpleasant, or even dangerous, complications. On the other hand, the difference may not be significant and the effect may be influenced by other genetic factors or interactions with other drugs. In any case, the dosage of most drugs can usually be adjusted to compensate for individual differences. No studies have shown improved patient outcomes from selecting drugs based on genetic information. Thus the idea of using genetic information for prescribing medications may have considerable promise, but its time has not yet come.
The Bottom Line
Genetic testing to identify alleged risk factors that have no proven corrective measures is a waste of money. As noted by Helen Wallace, Ph.D., Deputy Director of GeneWatch UK: “For most people, tailoring your diet to your genetic make-up is about as scientific as tailoring your diet to your star sign.”[12] There is also the concern that without proper regulation, genetic testing could be used to expand the drug market to healthy people who are said to be at high genetic risk. Many people could receive unnecessary medication and suffer the associated adverse effects. Finally, the underlying causes of heart disease, cancer, obesity, adult-onset diabetes, and other diseases might well be ignored, with serious implications for future health.
Stephen Barrett, M.D. operates www.quackwatch.com, where this article first appeared. Harriet Hall, M.D. is a retired family practitioner and Air Force colonel.
References
1. Unregulated genetic testing on the High Street and the Internet. GeneWatch UK, April 2002.
2. Great Smokies Diagnostic Laboratory announces new Genovations™ product line: Predictive genomics for personalized medicine. GSDL news release, March 15, 2002.
3. Genovations profiles. Genovations Web site, accessed Dec 29, 2002.
4. Patients guide to genomics. Genovations Web site, accessed Dec 29, 2002.
5. “Genovations” genetic test kits. GeneWatch UK, July 2002.
6. GeneLink, Inc. Form 10-QSB quarterly report for the quarterly period ended September 30, 2002.
7. GeneLink, Inc. reports revenue for third quarter. 2002. Business Wire, Nov. 14, 2002.
8. GeneLink Inc -- Growing, Expanding, Evolving! GeneLink Web, site accessed, Dec 29, 2002.
9. Barrett S., Homocysteine: A cardiovascular risk factor worth considering. Quackwatch, Aug 29, 2002.
10. Evans WE., Johnson J. Pharmacogenetics: the inherited basis for interindividual differences in drug response. Annual Review of Human Genetics 2:9-39, 2001]
11. GeneWatch UK response to the Human Genetics Commission’s announcement of a consultation into genetic testing services. GeneWatch UK press release, July 18, 2002.
12. Genetics and ‘predictive medicine’: Selling pills, ignoring causes. GeneWatch UK Briefing Number 18, May 2002
