If you could find out whether you’re going to develop a disease or not, would you?
With the advent of precision and personalized medicine, this has become a question that many people will need to consider. Using genetic testing, it is now possible for someone to find out if they will or are highly likely to develop a disease.
However, in the process of answering these questions, researchers, clinicians and patients are faced with a whole host of ethical dilemmas.
In this series, we’ll explore some of the ethical issues of genetic testing, including those surrounding consent and confidentiality and the roles of the parties involved.
What is genetic testing?
Genetic testing involves taking a sample of someone’s DNA – extracted from, for example, cells present in their blood or saliva – and analyzing it to identify any mutations. Some direct to consumer genetic testing companies use this information to make inferences about ancestry, but clinically, it can be used to assess if the mutations you possess have any implications for your own and/or your relatives’ health.
Health-related genetic tests can include, but are not limited to:
- Diagnostic testing – to confirm or rule out a genetic disease.
- Predictive and presymptomatic testing – to determine if someone possesses any DNA variations that increase the risk of developing a particular disease e.g. some BRCA gene mutations are indicative of a higher risk of developing breast and/or ovarian cancer. It can also involve testing for hereditary diseases that are not yet displaying symptoms, such as Huntington’s disease.
- Carrier testing – to identify mutations that may only be present in one copy in the person being tested, but if present in two copies, can cause a genetic disease. This can be used to inform couples about their risk of having a child with a specific genetic condition.
This can be carried out with a wide range of technologies, including:
- Single gene sequencing – this can be used when investigating a condition which is known to be associated with mutations in a particular gene.
- Whole genome or whole exome sequencing – useful for investigating risk for multiple diseases, or conditions that have been associated with mutations in more than one region of the genome.
- Cytogenetic analyses, such as karyotyping or fluorescence in situ hybridization (commonly known as FISH) – these techniques can be useful in diagnosing chromosomal disorders.
Why is it useful?
Genetic testing, when used as a diagnostic tool, is very powerful; not only can testing help to confirm or rule out a diagnosis, it can also help to identify the potential genetic origins of some of the rarest conditions. For example, the Deciphering Developmental Disorders study has successfully sequenced and analyzed the genomes of individuals with undiagnosed developmental disorders such that some now have a genetic diagnosis for their condition.
As previously mentioned, predictive genetic testing can be used to determine someone’s risk of developing a disease. Whilst it’s not possible to change someone’s genetic risk, anticipating the possibility of a condition can give people a reason to take steps to reduce the influence of environmental factors. For instance, an individual may have a particular genetic predisposition to developing lung cancer, but whether or not they smoke can contribute to their overall risk. The results of testing may also encourage the uptake of regular screening, such that a disease can be diagnosed and treated at an earlier stage.
The data obtained from genetic testing can also help to inform treatment. This has spun out a new field in medicine, known as pharmacogenomics, as well as contributing to improvements in cancer management.
As seen above, genetic testing is useful in a breadth of ways, many of which are helping to bring us closer to personalized medicine. With the knowledge gained by analyzing a person’s DNA, it’s possible that this information can be used to tailor healthcare to the individual.
Genetic testing and ethics
Whilst undoubtedly useful, genetic testing can also be the source of many ethical debates. Ethicists often use case studies, based on real or hypothetical situations to identify such issues and attempt to find morally (and legally) sound solutions.
Jodie is a 28-year-old woman who is thinking about having children. However, she has a family history of limb-girdle muscular dystrophy and is considering undergoing genetic screening to determine if she is a carrier of any variants (a.k.a. mutations in her genome) associated with the disease.
DNA is extracted from the blood sample provided by Jodie and it undergoes whole exome sequencing. Upon sequence analysis, it’s found that Jodie does not have any of the variants currently associated with limb-girdle muscular dystrophy. However, the person analyzing the data also checks for other common disease-associated variants. They discover that Jodie has a mutation in BRCA2 that puts her at a higher risk of developing breast and/or ovarian cancer.
A multitude of ethical issues are raised by this particular case, including the below:
- Jodie’s BRCA2 mutation means she’s at risk of developing cancer. However, this doesn’t mean that she is guaranteed to develop the disease and it was unrelated to the primary goal of testing. Does her clinician have a responsibility to inform Jodie of her risk? Should the possibility of additional findings be raised in the consent process?
- Jodie doesn’t possess any variants currently associated with the disease – some rare forms of limb-girdle muscular dystrophy are caused by mutations yet to be identified. If they are identified in the future and Jodie does in fact carry one such mutation, should she be re-contacted?
This case study highlights only a small sample of some of the ethical issues arising from genetic testing. To explore the key dilemmas in more detail, take a look at the articles linked below.