Genetic Testing Becoming the Norm
By Wanda K. Hartmann, Freelance Science Writer
Genetic testing is becoming commonplace. With the advent of new genetic testing companies, what does the future hold for diagnostic testing? Many Direct-to-Customer (DTC) genetics testing companies offer mail-in saliva test kits, similar to the first mail-in AIDS tests offered in 1986. Companies such as 23andme and Navigenics are offering a DTC tests for SNPs (single nucleotide polymorphisms), single mutations on the DNA backbone that may be linked to certain diseases. In addition, genetic tests for bipolar disorder and schizophrenia are coming on the market – offered by Psychnomics and SureGene, respectively. Other tests for Alzheimer’s may be coming as well. However, the tests do not offer 100% predictability. How will these future tests, the Genetic Information Nondiscrimination Act, and the interaction with patients, DTC genomics testing and healthcare providers come into play? Will genetic tests become as routine as blood tests?
The Genetic Information Nondiscrimination Act
An important bill was passed last year, the Genetic Information Nondiscrimination Act of 2007. In many ways, this bill opened the door for mass production of genetic testing, as it outlawed discrimination against individuals by health insurance companies and employers. This law grows out of the early sterilization laws in 1907-1981 that protected persons with genetic defects. Sickle cell anemia was one genetic disease that threatened discrimination against African Americans. One example of pre-employment genetic screening and discrimination was used at Lawrence Berkeley laboratory in California. This case resulted in a decision in favor of the employee. The Genetic Information Nondiscrimination Act has helped to protect the public from genetic discrimination and aims to allow consumers access to genetic testing and early detection of disease.
One SNP or the Whole Genome?
DTC genomic testing companies are not only offering a test for a single gene, but claim to be selling tests for a personal genome. In early 2007, the company 23andme started a new company based on a “personal genome web-based service.” The company was started by executives of pioneering companies in gene testing. Similarly, Navigenics offers, a “gene roadmap to health.” Curious about their services, in particular the issue of privacy of genetic information, I read their websites and contacted Navigenics. From the website information and response, it seemed that the customer service and privacy was of more concern to Navigenics than 23andme. Genome testing companies will gain power when they control genomic data. What rights does an individual have to their genome data files once they have mailed in their saliva? The temptation for genome knowledge and the long term exposure of an individual’s genome for information exchange is indeed both intriguing and worrisome. How much power do we place in the hands of the DTC genetics companies? What happens when these companies are bought out by others or change hands? How will policies change? The government can only control and protect the consumer to a certain extent. Eventually these genomic companies might be outsourced to other countries.
Mail Order Genome Test Results
As a doctor or health professional, how does one respond when a patent enters the office with a genetic test purchased through a mail-in saliva kit? What is the percentage error in these tests? How will the results be interpreted? Will the field of genetic counseling experience a huge growth? Speaking with a genetic counselor by phone or email in another state and eventually country is very impersonal. The NIH Genome 2004 study indicated that the risk of misinformation is not adequately transmitted and understood in DTC tests. Marketing on the internet leaves out the healthcare provider, a risky move, and leaves the burden on government agencies to oversee DTC testing.
Amniocentisis: The Most Frequently Used Test
In looking for the origins of genetic testing we should look to the most familiar genetic test, an amniocentesis. An amniocentesis is performed to check primarily for Down Syndrome and Cystic Fibrosis in pregnant women of advanced maternal age. The first genetic diagnosis of amniotic fluid was made in 1956 and published in the journal Nature. In 1968, Dr. Carlo Valenti made the first diagnosis of Downs Syndrome with a genetic test. Amniocentesis is regularly used as a genetic test in pregnancy. The results of this test have a profound impact on the mother. Care is taken to have appropriate genetic counseling available. The mental health aspect of finding out that you have a life threatening illness is just as important as finding out about a physical disease. Physical diseases that have been linked to genetic markers and tests are listed here:
Company
Year Genes Tested Disease
Myriad Genetics
2002 BRCA1 and BRCA2 Breast and ovarian cancer
2001 P16, CDKN2A or INK4A or MTS1 Melanoma
2000 MYH, MLH1 or MSH2, APC Hereditary Nonpolyposis Colon Cancer
Genzyme
2006 KRAS Non-small cell lung cancer
2006 CFTR Cystic Fibrosis
1999 nMLHI and hMSH2 Colon Cancer
deCODE
2007 TCF7L2 Type 2 diabetes
2007 PDE4D Stroke
Myriad, Genzyme and deCODE are three companies that have been developing genetic tests and have tests on the market for specific diseases. The company deCODE plans to enter the personal genome market and compete with 23andme and Navigenics. What does this mean for the patient/consumer and healthcare provider?
It means that not all tests are created the same. Different genetic tests will be looking for different genes, combinations of genes and gene linkages, possibly using slightly different technologies, with different variations in error. They will make judgments about different risk factors—how likely are you to develop the condition. Another factor is other non-genetic diagnostics tools that may either refute or support the genetic test. When it comes to a person’s health, a single test should not be the only predictor of disease, if there are other diagnostic tests available.
Advances in colon cancer cure rates alone are making it possible to receive diagnostic testing that is less painful and more technologically advanced. If you believe that you are at risk for a certain disease and have part of your genome tested, how will you follow up the genetic tests with other diagnostic tests? Would you change your lifestyle to minimize the risk? How might this change your life expectancy?
How Does a Patient Make Decisions Based on Genetic History and Tests?
Imagine you are one of 5-10% of the population with a family history of colon cancer. You make the decision to get a genetic blood test at age 39. There is a 1% chance that you will test positive for colon cancer at that early age. As you know you are already at risk, you might change your personal habits or diet. If the test came back negative, does it mean you are not at risk? No. There is error associated with the test and possible future environmental triggers. If the test came back positive you might be more cautious and agree to have a colonoscopy. Making these decisions in the absence of a doctor is not sound.
On the other hand, there are other diseases that have no other tests but genetic ones available. Many of these tests are for mental diseases. In the case of Alzheimer’s, only 25% of the cases are hereditary. Currently the NIH recommends against genetic testing for Alzheimer’s. There is not enough reliable data to make the test worthwhile. It is unclear how genetic testing will help.
Genetic testing is not a magic bullet, but advances in knowledge about gene linkages are important for the healthcare provider. Although there are tests available for many diseases (cancer, stroke, melanoma, cystic fibrosis and type-2 diabetes), many gene tests for diseases do not provide clear-cut answers. A Parkinson’s gene has been discovered in 20% of the people of Middle East origin. Genetics may only add a small increment of information to what we may already know – a sight predisposition to Parkinson’s.
In order to be an informed customer of the DTC genomics companies, a patient would need to start with a Ph.D. in genetics to understand what is being testing for. It is unclear what markers are included in genome testing and whether or not are they are true predictors in diagnosing disease. Many consumers may think they are getting their entire genome mapped, when in reality the test is only a portion of it. The cost and technology to date limit testing the genome for only a specific set of gene mutations. The cost of an entire genome map is prohibitively expensive for the average consumer.
Although it seems that the goal of DTC is to put power in the hands of the patient/consumer, in the process, the healthcare provider is potentially being left out. Patients need counseling both before and after they receive this test. Many people will receive counseling by phone or internet, not a high quality medium for healthcare services. This is a risky path to take. It places the burden on the uninformed patient. Knowledge can be powerful, but how does the knowledge of one’s genome change a life? When a genetic test for any disease becomes as easy as mailing in a test tube filled with salvia, it diminishes the importance of our lives and reliance on the medical field and a team of healthcare providers to guide us in important decision making.
Gene tests, counseling, and education of the general public on the matter of genetics has a long way to go. The science and biotechnology of genomic testing will only improve and become more affordable in the future.
