Direct-to-Consumer Genetic Testing:
Reliable or Risky?
Moderators: David H. Spencer1*and Christina Lockwood1
Experts: Eric Topol,2James P. Evans,3Robert C. Green,4Elizabeth Mansfield,5and Zivana Tezak5
In recent years there has been a dramatic increase in the
ease, as well as in the technical ability to accurately mea-
sure an individual’s genotype. These advances underlie
genotype informs the medical care they receive. Private
by providing direct-to-consumer (DTC)6genetic testing
that estimates the risk of disease for a customer, given
their genotype. Because these tests make claims about
medical conditions, they have come under scrutiny by
regulatory agencies. We ask experts in the field to com-
DTC genetic testing is based primarily on associa-
tions between common genetic variants and disease.
Do we have enough evidence about these associa-
tions to use them as genetic tests?
Eric Topol: Yes, without
question, in select cir-
cumstances. For several
actions, the information
a major adverse side ef-
fect (as with carbamaz-
epine) or to ensure effi-
cacy (clopidogrel). Also,
when there is clear evi-
dence of heightened risk
(e.g., 2-fold or greater) for a common disease, such as
diabetes, heart attack, colon, melanoma, or other can-
cers, there can be actionable information to get appro-
priate screening (e.g., colonoscopy) or potential pre-
ventive steps (e.g., protection from the sun). As we
move toward sequencing and identification of rare or
low-frequency variants that have high penetrance, it is
unlikely that the heightened risk from the previously
identified common variants will go away.
James Evans: We clearly
do not. This is best dem-
straightforward studies in
which the same sample
was sent to leading DTC
companies for analysis.
wildly divergent risk esti-
porting “above average,”
“below average,” and “av-
risk factors is insufficient to aggregate single-nucleotide
polymorphism (SNP) genotypes into reliable estimates
Robert Green: Yes. The
sensible application of
even modest probabilis-
tic risk factors to influ-
ence individual human
behavior or medical in-
tervention is the basis for
considerable progress in
modern public health.
Thus, if handled respon-
sociations between ge-
1Washington University/Barnes-Jewish Hospital, St. Louis, MO;2Scripps Trans-
lational Science Institute, The Scripps Research Institute, La Jolla, CA;3Depart-
ment of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC;
4Division of Genetics, Department of Medicine, Brigham and Women’s Hospital
and Harvard Medical School, Boston, MA;5U.S. Food and Drug Administration,
Silver Spring, MD.
* Address correspondence to this author at: Washington University/Barnes-Jewish
Hospital, Box 8118, 660 S. Euclid Ave., St. Louis, MO 63110. Fax 314-362-1461;
Received June 20, 2011; accepted July 5, 2011.
6Nonstandard abbreviations: DTC, direct-to-consumer; SNP, single-nucleotide
polymorphism; FDA, U.S. Food and Drug Administration.
Clinical Chemistry 57:12