Leading genetic testing companies are providing clients with widely divergent
and inaccurate predictions of their chances of developing serious diseases.
That is the finding from tests conducted by different firms on the same
person.
Using my own DNA, I approached three firms who between them provide the
majority of genetic tests for common diseases in the UK. They gave
contradictory assessments of the risk I faced of developing illnesses,
including Alzheimer’s and glaucoma, and a confused verdict on my risk of
suffering heart problems.
The findings reveal that those paying up to £825 for the tests may be
receiving either misleading assurances that they face low heath risks or are
being caused needless anxiety by warnings of high risks.
Lord Taverne, a member of a Lords select committee investigating genetic
testing, said: “This [investigation] confirms that some of the commercial
genetic tests can be very misleading and harmful. It may cause unnecessary
anxiety and people may take action based on an unreliable diagnosis.”
Though in its infancy in the UK, the market for genetic testing is predicted
to grow fast.
Several companies are already well established.
The first I approached was GeneticHealth, a British firm which charges £825
for a test and consultation. Its literature states that it can help
customers to “live a longer active life, feel and look better, slow the
ageing process and avoid disease by effective prediction and detection”.
The other two firms approached were deCODEme, based in Iceland, which charges
$985 (£557), and the American group 23andMe, which charges $999.
Viewing their results proved to be more baffling than enlightening. For
example deCODEme said my risk of developing exfoliation glaucoma, which
causes loss of vision, was 91% below average. Yet according to 23andMe, I
was 3.6 times more likely to get it than average.
For age-related macular degeneration, deCODEme put my risk at 20% lower than
average, while 23andMe said it was 62% higher.
According to deCODEme, my risk of developing Alzheimer’s was 74% above
average, while GeneticHealth said my genes were associated with “a fourfold
increased risk of developing Alzheimer’s disease by your late 80s”.
According to deCODEme, my risk of a heart attack, angina or sudden cardiac
death is 54.8%, which is 6% above average. By contrast, 23andMe said my risk
of a heart attack between the ages of 45 and 84 was 17.5%, below average.
Yet another assessment came from Paul Jenkins, the clinical director of
GeneticHealth, who said my risk of cardiovascular disease was “low to
moderate”.
According to deCODEme, I had a 2% higher than average risk of developing
Crohn’s disease, a chronic bowel condition, while 23andMe put it at 47%
lower than average.
GeneticHealth said my genes put me at “significantly increased risk” of
hypertension, or high blood pressure, yet 23andMe defined me as at
“moderately higher risk”.
With so many contradictions and inconsistencies I was left not knowing what to
believe. There were, however, five conditions for which both deCODEme and
23andMe put me at similarly reduced risk – celiac disease, colorectal
cancer, lactose intolerance, psoriasis and prostate cancer.
Christine Patch, genetic counselling manager at Guy’s hospital in London and a
member of the Human Genetics Commission, said the companies had identified
my gene types correctly, but that they often based their analysis on
different genetic variants.
Even when they were looking at the same variants and research, they could be
interpreting them differently. “The science on this is still really work in
progress,” she said.
Cecile Janssens, of the Erasmus University Medical Centre in Rotterdam and
author of an academic evaluation of the statistical weakness of seven other
genetic tests, said: “This is the first time I have seen the results of the
same sample being tested.
“It illustrates perfectly how what these companies are doing is premature.
“Although genomic profiling may have the potential to enhance preventative
interventions, to date the scientific evidence is insufficient. It could
take years if not decades before lifestyle and medical interventions can be
responsibly and effectively tailored to individual genomic profiles.”
The firms selling genetic tests are operating in a regulatory vacuum. The
Medicines and Healthcare Products Regulatory Agency believes it does not
have the resources to oversee the sector, and a senior figure at the
Advertising Standards Authority said it felt underqualified.
Asked why the results varied so widely, Kari Stefannson, chairman and
co-founder of deCODE Genetics, said: “We are very confident that we
understand better than anyone which markers correlate with a given level of
disease risk.
“Having worked in this field for well over a decade, I have serious doubts as
to whether dot-com companies that out-source both the basic science and the
genomic analysis can deliver the sort of quality results that we think the
public and medical establishment rightly demand of this new component of
healthcare.”
Brian Whitley, founder of GeneticHealth, defended his company’s assessment of
my risk of getting Alzheimer’s, saying: “Our risk has been taken directly
from the Alzheimer’s Society website and we believe they are the most
moderate and core source.”
Brian Naughton, a scientist at 23andMe, said the results depended on “which
SNPs [single nucleotide polymorphisms, or genetic variants] you include, so
if deCODEme have one more SNP than we do then you expect a difference.
Co-founded by Anna Wojcicki, wife of the Google co-founder Sergey Brin,
23andMe asks customers to sign a legal waiver stating they understand their
service is for “research and educational use only”.
The firms point to their successes, saying some clients have been given an
early diagnosis of their condition.
Lauralee Nygaard, a dentist, in Spokane, Washington state, had a stroke three
years ago and doctors could not find the cause. A deCODEme test identified a
susceptibility to atrial fibrillation, and she now takes blood-thinning
drugs.
Testing for single gene diseases has been available on the NHS for more than a
decade. Women with a family history of breast or ovarian cancer receive a
test for BRCA gene mutations. Multi-gene disorders are more complex.
So far an estimated 2,000 Britons have taken private gene tests and Stefansson
said: “My prediction is within five years every reasonably educated person
in western society will have had a genetic profile.”
Helen Wallace, of the campaign group GeneWatch, said: “At present there is a
regulatory black hole that allows companies to mislead people about their
health. Handing over your genetic information [also] increases the
likelihood that insurers will discriminate against you in the future.”
Our genomes are all remarkably similar, but the differences make us who we are. The same can be said of genetic testing services. We at deCODE were not at all surprised that Mr. Fleming found that he got some varying results from the three genome scans. See my response on www.decodeyou.com
Edward Farmer, Cambridge, UK
Anyone with their own DNA data, as provided by companies such as the ones mentioned in this article or others, should use the (free) Promethease (www.promethease.com) software that checks results against the SNPedia website, since SNPedia is independent of all these (for-profit) companies.
Greg, Bethesda, MD, USA