Getting a grip on genetic testing

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  • NATURE MEDICINE VOLUME 9 NUMBER 2 FEBRUARY 2003 147

    EDITORIAL

    VOLUME 9 NUMBER 2 FEBRUARY 2003

    Getting a grip on genetic testingThe genetic testing industry is poised fora major expansion. That much is evidentfrom the discoveries that now fill thepages of medical and genetics journals.More than 400 genetic tests are currentlyavailable. At least one major companyhas launched a television and magazinead campaign to market its tests to con-sumers, and others accept blood samplesdirectly from customers, bypassing med-ical counsel.

    In the United States, essentially no reg-ulations exist to meaningfully evaluategenetic tests, including their clinical va-liditythat is, their sensitivity and pre-dictive value. Certainly some form ofregulation, if only for accurate and de-tailed labeling, should be required.

    Nearly all genetic tests bypass the Foodand Drug Administration (FDA). Thatsbecause most new tests are categorized asservices, which the FDA does not regu-late. Such tests go through anotheragency, the Health Care FinancingAuthority, which assesses lab quality butnot the clinical validity of a test. The FDAdoes regulate tests categorized as kits,which provide labs with reagents, but thecommittee that provides advice on suchkits has not evaluated a new one in morethan two years.

    This is the right time to develop regula-tionswhile the industry is still nascent.The reproductive services industry is astriking example of what can go wrongwhen a new technology moves too fast forthe FDA. In vitro fertilization clinics offernew services without any federal oversight.As reproductive medicine and genetic test-ing intersect in pre-implantation genetictesting, the problems will only compound.

    Anticipating the growth in genetic test-ing, the Department of Health andHuman Services (DHHS), which overseesthe FDA, set up the Secretarys AdvisoryCommittee on Genetic Testing in 1998.The committee grappled with balancingoversight of a mushrooming area withoutquashing it through over-regulation.

    Members strongly recommended that theFDA regulate tests classified as services.The DHHS agreed, saying, FDA shouldbe the federal agency responsible for thereview, approval and labeling of all newgenetic tests.

    But since then the situation seems tohave regressed. The FDA informed thecommittee members that it was reconsid-ering FDA oversight of genetic testing,and then the DHHS did not renew thecommittees charter. The DHHS has sincecreated a new committee with, so far, abroad but rather vague mandatetheSecretarys Advisory Committee onGenetics Health and Society. Its unclearwhether the regulation of genetic testingis even on the agenda. The agencies seemto have arrived at a stalemate, and giventhe trend against regulation in the Bushadministration, things may stay that wayfor some time.

    The Advisory Committee on GeneticTesting addressed other issues, includingthe need for follow-up data once a test hitsthe market. Statistical data that includeshow patients fared after testing could re-fine the clinical value of such tests.

    What does lax regulation mean for theaverage consumer? Genetic tests are al-ready available over the Internet, someclaiming to help people customize med-ications, vitamins or foods. Selling snakeoil over the Internet is nothing new, butwhen people dont have access to healthcare, or worry that their results may notremain private, their vulnerability to suchmarketing increases.

    Complicating the issue is the variety ofgenetic tests available. The results of sometests, mostly for rare disorders, offer clearguidance on prophylactic treatment.Others may also provide clear informa-tion, but the implications can hit peopleexceptionally hard; a 1999 study in theAmerican Journal of Human Genetics foundthat of 4,527 people tested forHuntington disease, 10 attempted suicidebefore the onset of symptoms.

    Undergoing the most commercial devel-opment now are tests that examine themurky area of predisposition to complexdisorders. Such tests require a fairly sophis-ticated understanding of genetics, andthey are highly susceptible to misinterpre-tation, even by medical professionals. OneNew England Journal of Medicine study of177 patients who were tested for muta-tions in the colon cancer gene APC foundthat in about one third of cases physiciansincorrectly assessed the resultsnot realiz-ing that a negative result does not precludeunknown mutations in APC.

    For people who have never heardphrases such as modifier allele or in-complete penetrance genetic tests mayseem at first to offer a crystal ball. Buttheir views often shift after getting advicefrom a genetic counselor. Certified coun-selors can explain the subtleties of genet-ics, and advise patients and their familiesabout the implications of the results.They can advise clients that testing nega-tive for a mutation does not mean theywont develop cancer. Or that if they dotest positive, it does not mean their sisteralso has a mutated gene.

    Most patients may grasp the concept ofodds, if properly informed. What manymay not be able to understand, however,is how their odds have been derived. Andneither may the health care providerswho administer genetic tests. As moretests become available, more health careworkers without specialized training willbe called on to administer them. Clearlylabeling and describing tests that havethoroughly been scrutinized by expertswould go a long way towards increasingthe knowledge.

    It is essential, especially for certainclasses of genetic tests, that people haveaccess to a health care professional, andthat the professional be well trained andaware of the meaning of the tests they ad-minister. At the very least, when peoplechoose to be tested, they should knowwhat theyre getting themselves into.

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