01 October 2007
Science writer and author of 'DNA Banking: Worthwhile? Ethical? Socially Acceptable?' - a dissertation submitted for the MSc in Science Communication, Imperial College London.Appeared in BioNews 427
But sequencing the human genome was just the beginning. Now, scientists face the painstaking process of finding out how the remaining 0.5 per cent makes us unique. Within this relatively tiny amount of variation in our genetic makeup exists a complex network of literally thousands of genes potentially responsible for differences in our hair or eye colour, our susceptibility to a particular disease, or our response to a particular drug treatment. To some extent, this genetic variation may even help define our individual personalities and behaviours.
There is now good evidence that many of the common diseases widespread in today's society, such as cancers, heart disease and diabetes, are the product of complex interactions between environmental and genetic determinants; a belief broadly shared by the wider public. With the additions of the completed International HapMap, a project to categorise all the common genetic variants that occur among humans (2), and a set of new technologies that can quickly and accurately analyse whole-genome samples for genetic variations that contribute to the onset of a disease (3,4,5), researchers now have a complete set of research tools that make it possible to find the genetic contributions to common diseases.
Although human genetics research has already lead to an increase in our understanding of the genetic basis of many single gene diseases, scientists aren't yet even close to unearthing all the genes that contribute to complex multifactorial diseases. But despite ongoing debates over the power of genetics to estimate common disease risk, it is widely believed that genetic information will become increasingly important in healthcare. This has lead some experts to suggest that such information would be richer if people today chose to bank their DNA prospectively, in order that their relatives could access this data for genetic testing in the future.
Consider the following example: A family has a strong history of breast cancer. Consequently the daughter of an affected member of the family wishes to be tested for mutations in the BRCA1 or BRCA2 genes - known to be responsible for around 1 in 10 breast cancers. If she is tested directly, and the test results are negative, this could mean one of two things: That her cancer is non-hereditary (i.e. she and her biological relatives are at the normal population risk for breast cancer), or that her cancer is hereditary but it is caused by another gene yet to be discovered (i.e. she, and potentially other biological relatives, are at increased risk from breast cancer). Rather like searching for a needle in a haystack, receiving a negative result for a mutation search in an unaffected person offers no additional information about their risk of developing breast cancer, leaving them unable to make an informed choice about whether or not to undertake clinical interventions, such as regular screening or prophylactic surgery.
Now imagine that we first test for BRCA 1 or 2 gene mutations in the daughter's mother, who has had breast cancer. A negative result would again be uninformative, because it could mean her breast cancer is either sporadic or is caused by a different gene yet to be discovered. However a positive result would confirm that the cause of the breast cancer was a particular mutation in either the BRCA1 or BRCA2 gene. Since the incidence of BRCA1/2 gene mutations in the population is rare, it is then possible to test the daughter for the same mutation, this time giving an informative result: If the daughter's result is positive, then she knows she has inherited the mutation from her mother and is also at increased risk from breast cancer. If the daughter's result is negative, she knows that she has not inherited the gene mutation from her mother and is at normal population risk from breast cancer.
This example helps to explain why genetic testing is a two-step process, in which a genetic risk factor must be identified in an affected family member before it becomes informative for unaffected family members to undergo genetic testing. Although there is ongoing debate, some experts speculate that in the future it may be possible to carry out genetic risk analysis for a whole host of common complex diseases. But what might happen in the case that an individual doesn't have a living relative affected by the disease at the time when testing becomes available? At the moment, nothing happens.
So those who could benefit from prospective clinical DNA banking might include:
a) Those who have a family history of a disease, but who have tested negative for the genetic tests currently available to them.
b) Those with a family history of a disease for which there is promise of a genetic test becoming available in the future, but none available at present.
c) Those who wish to make their DNA available to their relatives in anticipation of as of yet unforeseen uses in the future.
There are as of yet no private clinical DNA Banks in the UK, although a few are beginning to emerge in the US, such as that launched by the company 'Prevention Genetics' earlier this year.
While acknowledging that genetic information is potentially sensitive by nature (6;3.36) and that future developments, such as increased use of genetic information for prescribing purposes, will mean that genetic information may need to be stored for future use (6;3.37), the Human Genetics Commission (HGC) admits that it will probably not be feasible for separate arrangements to be made for the storage of genetic information within the UK health service. The lack of resources for DNA storage within the NHS means that the need for such services may exclusively be met within the private sector.
The recent Icelandic Health Sector Database saga, in which the private biotech company 'deCODE Genetics' faced huge controversy and criticism over the award of an exclusive license granting access the nations health care records (7), is a reminder of how easily new technologies can be influenced by powerful societal forces.
The social acceptability of private DNA banking enterprises will depend largely the willingness of service providers to confront the social and ethical issues raised by this technology and, in doing so, on their ability to provide safeguards and levels of transparency sufficient to guarantee public confidence. To achieve this, they will need to engage members of the public from the outset to ensure that company policies reflect public attitudes and values. Without such reflexivity, there is a danger that those who stand to benefit may forego opportunities to bank their DNA over ambivalence about potential benefits or fears about potential harms.