Posted by: fidouglas | October 18, 2010

A Little Knowledge is a Dangerous Thing

Our individual genomes contain many clues as to which diseases we are likely to acquire during our lifetime. It is now 2010, just seven years after the completion of the first complete draft of the Human Genome Project, and a number of commercial enterprises such as 23andMe are offering personal genome analysis services for just US$399: The client pays their money, spits into a tube, and sends it to the lab. Ten weeks later, they get their results back and can learn about their probability of developing a number of diseases.

This is quite a novelty, offering a new insight into our health, perhaps even giving the impression of allowing us to predict the future. Yet, many conditions such as heart disease and diabetes are dependent on many genetic and environmental variables. Whilst testing can offer information about an individual’s probability of developing the disease relative to the general population, it usually cannot say definitively whether they will get the disease.

Not only do the results overlook environmental factors, but they fail to account for genes which may interact with those being tested. The current lack of regulation means that commercial enterprises can make claims based merely on correlations, sometimes without any understanding of the precise genetic mechanism , and linking genes with diseases where rigorous testing has not taken place. This has led to criticisms by a number of academics in the field of genetics —speaking about ‘Genetic Health’, a personal genome analysis company like 23andMe, Dr Paul Pharoah, a genetic epidemiologist at Cambridge University, explained his belief that “there is little hard science behind most of what is claimed”.

Lack of specificity in testing may lead to unfounded concerns arising where people are identified as having an increased risk of acquiring a disease. People discovering they are more likely to develop type II diabetes may make beneficial lifestyle changes in order to reduce their chance of becoming diabetic. But whilst one individual may make positive changes to their life, another may become unduly worried and upset by this news. If the positive test result is in some way flawed, that concern and stress becomes completely unnecessary.

Although screening specifically for Huntington’s disease is not currently offered by commercial providers and tends only to be offered by physicians to those who are already thought to be affected, it demonstrates the negative impacts associated with a genetic diagnosis. Patients who receive a positive result in the screening have an increased chance of committing suicide—as a precaution, individuals with suicidal ideation are not screened for this disease.

This highlights the need to consider the benefits and implications of testing on the individual concerned, and this is particularly true in conditions such as Huntington’s disease where no cure nor effective treatment is yet available.

However, tests for Huntington’s disease occur in a clinical setting, where genetic counselling is offered to patients and often their relatives. Prior to the test, patients can discuss their options with a knowledgeable counsellor, make an informed decision about whether or not to go ahead with the test. If they do, they receive follow-up counselling, with support offered in light of the test results. In contrast to this, the majority of commercial providers do not offer such support. Instead, they act as detached third parties, hand out diagnoses from poorly-understood data and show seemingly little regard for the individuals whose lives they are affecting.

Commercial set-ups offering genome analysis are playing a dangerous game. They are providing customers with information about diseases to which they are predisposed, based on evidence which in many instances is largely unfounded. Sure, technology has come a long way, but it’s got far to go; until more research is done, personal genomics offers nothing except for a bit of a novelty. So I’ll keep my $399 dollars, 23andme, until you can come up with something worth buying.

NB:  I wrote this a little white ago. Since then, 23andme have started offering two types of service – the ancestry screen and the medical screen. The medical screen is now $429.


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