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Genetic: Testing Turn the Pages of Your Own Book of Secrets

By Kathy Lange

Genetic testing is now available to everyone who can afford it. Just imagine the possibilities.

A blood sample is taken. At the tip of the needle sits the nucleus of one of your white blood cells, a virtual book of secrets about you. You can read the full-length tome or you can peruse an abridged version—either one able to tell you whether you are likely to be obese or suffer from macular degeneration or even marital discord. Developed by scientists, this wondrous resource is now available for you to use in the privacy of your own home. Wow.

Not only can genetic testing determine if a potential mate is incompatible immunologically (histocompatibility), but it now appears that it can predict marital discord as well. A recent Swedish study has found that a gene variant may be responsible for marital infidelity in males. As reported in the Proceedings for the National Academy of Science, of the more than 1,000 males studied, those with two copies of a gene variant had twice the risk of experiencing marital dysfunction with the threat of divorce, than those with just one copy or no copies of the variant. Some fear the discovery could lead some people to insist upon genetic testing before making a personal decision about love and marriage, emphasizing that, although the presence of the gene variable is a powerful factor, it is just one factor that determines marital behavior. Relationships have many dimensions—sexual attraction, romance, and loyalty—that could shape the decision to remain monogamous. Defenders of the test say, if used correctly, the information could help a man overcome his behavior. Armed with knowledge that he possesses the mutation, a man could better resist the occasional temptation, thinking, oh, that’s just my DNA acting up.

The DNA Test Kit Delivered to Your Door

Utilizing genetic discoveries, personal genetics companies such as 23andMe, Navigenics, and deCODE genetics offer several options: a full sequencing of all 23 chromosomes (a genome) in the companies’ laboratories or a more limited self-test that looks at certain genes for common conditions such as asthma, heart disease, diabetes, and cancer. In either case, you must first fill out a questionnaire that asks for your date of birth, address, and details about your ancestry. If you are taking the self-test, companies send out a DNA test kit (such as 23andMe’s “spit kit”) with instructions on how to collect the DNA sample (spit or cheek cells). You then send it back via an overnight delivery service.

The company translates the base pairs in your DNA sample into a code, which is analyzed and loaded onto a secured, encrypted system on the company’s website, creating a personal profile. A digital representation of your 23 pairs of chromosomes showing your health-status data can then be printed out. On one company’s printout, red marks show a predisposition to a condition, the green marks show a decreased risk of a condition and yellow marks show average risk.

The cost of genetic testing varies, depending upon whether you are getting an entire genome sequenced or a more limited test. For the full sequencing, the cost is about $350,000. The cost for the more limited testing can range from $399 to $2,500.

The Science Behind Genetic Testing

The science behind the genetic tests now being commercially developed is well established—you may remember the basics from biology class: There are 23 chromosome pairs in almost every human cell. Lined up along the sides of the chromosomes, like beads on a string, are a series of genes comprised of DNA (deoxyribonucleic acid). DNA, itself, is formed by 3 billion pair of four different chemicals, represented by the letters A, T, C, and G. The various sequences of these chemicals, called base pairs, determine the growth and behavior of our cells and our predisposition to diseases and conditions.

Normally, the sequencing of the base pairs within the 100,000 genes in our bodies should follow a very specific pattern, such as the one tracked down by scientists in 2003 as part of the international 15-year collaboration known as the Human Genome Project. However, sometimes, either through exposure to environmental toxins, radiation, or some other factor, a mistake is introduced into the DNA sequence—a mutation. When large groups of people share the same mutation, they’re known as single nucleotide polymorphisms (SNPs).

Although every disease or condition has a genetic basis, given that there are three billion base pairs, trying to determine which genetic anomaly causes a disease is like looking for a needle in a haystack. But scientists are now benefiting from increasingly sophisticated sequencing techniques and detailed maps identifying the general region of the gene in which the SNP is located, allowing them to look for single changes in only hundreds of thousands—as opposed to three billion pair—of the famous A, T, C and G chemicals. So far, scientists have developed maps for 1,500 diseases. Mapping for hundreds more is ongoing—including those for schizophrenia and bipolar disorder at Johns Hopkins University. The mapped sequences will be compared to a patient’s own genetic sequences to determine that patient’s likelihood of developing a disease or condition.

Are We Opening Pandora’s Box?

Rather than being an exotic toy for the wealthy, proponents of genetic testing view it as a useful tool for those who want deeper insight into the genetic basis of their health-related characteristics. Genetic testing can motivate a person to change his or her behavior (stop smoking, lose weight, etc.) as well as to be more proactive in managing risk (get more frequent check-ups). And for cancer and other conditions, gene analytical tools help in “pharmacogenomic” testing, which is becoming standard practice in selecting drugs and doses. For example, scientists have found that a base pair mutation in a certain gene can result in a 50 percent reduction of a person’s response to pain medication.

Additionally, with detailed and accurate genetic information from large groups of people, genetic testing has potential to analyze and treat epidemiological risks across populations. Soon, personalized medicine—which will utilize drug therapies tailored to each person’s body, improving effectiveness and reducing side effects—will depend upon genetic testing. In the not-too-distant future, as is done now with mice and other laboratory animals, genetic testing will be used to physically alter our genetic blueprint.

Critics of genetic testing point out that there are risks with genetic testing. Tests that readily reveal an individual’s genetic endowment could cause embarrassment or stigma. Employers seeing the results could deny people jobs or fire them. People could use the genetic information to decide whether potential mates are bad marriage prospects. And although Congress enacted the 2008 Genetic Information Nondiscrimination Act (which prohibits health insurance companies from discriminating in providing coverage to and in setting rates upon the basis of genetic predispositions), the law does not cover life, disability, or long-term care insurance, or Medicare or Medicaid, which are entitlements, not insurance. For these reasons, genetic testing should be treated in much the same way as HIV test results—as potentially discriminatory and stigmatizing information. Before sharing your genetic information, you should carefully consider how others might use it.

Even if you choose not to share your test results, your own knowledge of them could have negative consequences. As stated on one personal genetics company’s website, the information may evoke strong emotions and may alter your life and worldview. While the testing could lead to a diagnosis and cure of some diseases, why find out risks for those that have no cure? For example, genetic testing could reveal that you are at risk of developing Alzheimer’s disease. At age 25, would you really want to know about a disease that could result in a sharp cognitive decline in your early seventies? Such knowledge may change your ideas about getting married or having a family, or affect your career pursuits. Depending upon the individual, the information offered by such tests may cause more harm than good.

Also, anyone undergoing testing should consider that the tests and results are not error-proof. Although the laboratories administering genetic testing are federally licensed, the FDA is not currently enforcing existing performance standards, and some of the data generated during the laboratory process may be incorrect or inconclusive. A real concern is that the data derived from genetic testing could lead people to take unwarranted actions. Thus, especially in connection with diseases or conditions for which there currently exists no treatment, participants should consult with a trained geneticist or genetic counselor to assist them in interpreting the results.

Most importantly, it should be emphasized that genes are only one factor among many that influence who you are. Diet, lifestyle, environment, and even luck can be equally or more significant in determining your future. For this reason, the tests don’t actually predict whether or not a person will contract a disease or condition but, instead, offer limited information about how much more likely he or she is to develop one than someone who has “normal” sequencing. Given the incomplete picture presented by genetic testing, critics say, your family history still is the best predictor of what diseases or conditions you are at risk of developing.

Some personal genetics companies will limit the information to only the conditions that they think you should know about, while others allow you to choose which information you want to receive. In the final analysis, only you can determine if genetic testing is right for you. Although genetic testing results may be imperfect, they may someday lead to better diagnoses and cures. In the meantime, they could enable you to better understand why you are the way that you are. And, if that leads you to lose weight and take vitamins, you just might be able to improve your biological destiny.

Kathy Lange is a lawyer and freelance writer of health articles. She resides with her husband and son in Davidsonville and Stevensville.

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