Genetic testing and counselling
If we lay out diseases on a scale, on one end are those highly influenced by environmental and lifestyle factors. At the other end are diseases with far stronger genetic contribution, which include Huntington disease, haemophilia, and Marfan syndrome. Some diseases are clearly linked to a specific genetic variant, which genetic testing can help uncover. Testing tells whether an individual has the specific genetic variant and is thus predisposed to develop the disease. Genetic counselling, performed both pre- and post-test, guides patients on understanding their risks and to consider their next step — how likely the disease will occur, should genetic testing be done, and how to mitigate severity when the disease strikes.
Genetic services in Singapore
In Singapore, genetic testing and genetic counselling are overseen by clinical geneticists (doctors who have subspecialised in genetics) or other subspecialists trained in the genetics of a particular disease. Often, clinical geneticists work with genetic counsellors when providing counselling to patients.
“We can classify test takers roughly into two groups,” says Associate Professor Roger Foo, Cardiac Department, National University Heart Centre, Singapore (NUHCS). “Those who test for a medical reason, and those who test just out of curiosity”. In Singapore, most of the patients seen by a clinical geneticist or genetic counsellor fall into the first group.
In Singapore, most of the patients seen by a clinical geneticist or genetic counsellor fall into the first group.
Assoc Prof Foo and genetic counsellor, Ms Yasmin Bylstra, work with patients who have inherited cardiac conditions such as cardiomyopathies, connective tissue disorders, and arrhythmias. At the National University Cancer Institute, Singapore (NCIS), Associate Professor Lee Soo Chin heads the Cancer Risk Assessment and Genetics Clinic, which offers testing for BRCA1/2 mutations and cancer syndromes such as Lynch syndrome. Meanwhile, Associate Professor Denise Goh Li Meng, Department of Paediatrics, NUH, offers testing for many genetic conditions. She sees a wide range of patients, from couples planning to start a family to newborns and adults.
For the second group, ie those who text to satisfy their curiosity, Direct-to-Consumer (DTC) tests are popular. These are tests that are available to the public and do not require consultations with doctors. Some tests provide information on genetic health risks, while others tell consumers their ancestry. The appeal of these tests lies in their convenience, relative affordability, and non-invasiveness. Consumers order a kit, provide a saliva sample, and mail it back to the genetic testing company. In due course, customer receives a genetic profile report. However, DTC tests come with their own set of issues (see Facts Box). In Singapore, DTC genetic tests are strongly discouraged.
A genetic counselling session
During the session, the genetic professional will learn about the patient’s family history. Typically, a patient provides notable medical histories of at least three generations of his or her extended family, which includes grandparents, aunts, uncles, and first cousins. Information on diseases and test results will also be gathered. Besides information on inherited disorders, the genetic professional will also learn about the patient’s lifestyle, diet, other environmental exposures, and medications.
Genetic counselling involves not just scientific explanations of risks, probabilities and disease courses; it also includes a psychological component, offering psychosocial support, and helping patients cope with their situation. Pre-test, genetic professionals help patients understand testing options and implications of testing, to ensure informed consent. Post-test, genetic professionals help patients navigate the array of steps they can take based on their genetic profiles, and provide a roadmap showing the implications of each option. These options may include lifestyle modifications, reproductive planning, palliation, and more. The genetic professional may also make healthcare recommendations for at-risk family members or offer testing. Importantly, rather than prescribe a course of action, the genetic counselling session provides the patient with the relevant information to make a decision about testing or treatment and how to communicate information about their genetic condition to at-risk family members. Unlike typical doctors’ visits, genetic counselling sessions are longer and can last up to 45 minutes or an hour.
Assoc Prof Denise Goh cautions that genetic tests and results are complex, and understanding and communicating them requires specialised domain knowledge. No test is perfect and a trained professional is better able to differentiate false negatives from true negatives, and false positives from true positives when interpreting results. They are able to tell if a particular variant is pathological, benign, or has unknown significance. Even if a pathological variant exists, a genetic condition may not have a 100% evolution rate. One example is BRCA1/2 mutations, where not all carriers will go on to develop breast cancer.
Ethical issues
Although anyone can request for genetic testing, Assoc Prof Roger Foo recommends having very clear reasons for doing so. The knowledge that one carries a pathological variant may be burdensome or even traumatic for some. Thus, the decision to test should not be taken lightly.
The results from genetic testing are permanent, out-living the individual. As such, testing may have implications for insurability and employability. Although insurance agencies and employers do not have the right to access an individual’s genetic information, they can request applicants to declare any genetic information, increasing the risk of genetic discrimination.
Another ethical issue centres round underage, asymptomatic patients whose parents want them to be tested for genetic conditions that manifest later in life and for which no early intervention is available. Testing thus takes away these children’s right to make informed decisions in the future. Current guidelines state that for such patients, testing should be delayed until these children reaches adulthood and can make their own decisions.
The privacy of genetic information concerns not only the individual, but their relatives as well. Due to a shared genetic heritage, genetic testing of one individual may reveal information about a relative, such as a parent, regardless of that relative’s wishes.
Another ethical issue is that of incidental findings, where mutations unrelated to the patient’s symptoms are picked up during a test. It is not possible to “un-know” a piece of information, although Ms Yasmin Bylstra explains that patients can make the choice whether to receive incidental findings. Incidental findings also come with a whole host of ethical considerations, which have been extensively debated.1
Some experts hold the view that knowing may be pointless if there is no treatment (termed medically non-actionable). To this, Assoc Prof Goh posits the concept of utility to patients, which is distinct from medical actionablility. Whether or not a treatment or cure exists, knowledge about their risk for a disease allows the patient to plan for the future and make necessary adjustments.
Conclusion
Genetic testing can reveal useful information regarding health risks, allowing us to prepare for what may come. However, it is not an unmitigated good; risks to genetic testing exist and need to be weighed against any benefits. Given the bewildering amount of technical information produced by a genetic test, geneticists and genetic counsellors are invaluable in helping patients make sense of the data and find their way to a decision.
References
1. Roche, M. I., & Berg, J. S. (2015). Incidental Findings with Genomic Testing: Implications for Genetic Counseling Practice. Current Genetic Medicine Reports, 3(4), 166-176. doi:10.1007/s40142-015-00759
2. Lim, P. et al. (November 2005). Genetic Testing and Genetic Research: A Report by the Bioethics Advisory Committee Singapore. Retrieved from http://www.bioethics-singapore.org/images/uploadfile/55211%20PMGT%20Research.pdf
3. Gutierrez, A. (2013, November 22). Premarket Approval/Adulterated [Letter written November 22, 2013 to 23andMe, Inc.]. Retrieved June 6, 2017, from https://www.fda.gov/ICECI/EnforcementActions/WarningLetters/2013/ucm376296.htm
Facts Box 1:
Drawbacks of Direct-to-Consumer (DTC) Genetic Tests
In their 2005 guidelines, the Bioethics Advisory Committee of Singapore strongly discourages the use of DTC tests2 due to several ethical concerns.
Uncertain quality:
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- For disease risk: only one has been FDA-approved — 23andMe Personal Genome Service Genetic Health Risk.
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- 23andMe has a history of selling DTC tests without FDA approval, despite attempts by the FDA to help the company comply with regulations. In 2013, the FDA issued a warning letter3 to stop marketing of the test.
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- Although consumers are provided with information to help interpret their disease risk, inaccuracies or misunderstanding can arise without consultation with genetic professionals.
- For ancestry testing, heritage results differ among companies, depending on the sample database, how regions are divided, and how many genetic markers are used.
Genetic information privacy:
- Some providers have questionable privacy terms, eg, AncestryDNA™’s policy states that it can use genetic information in perpetuity, royalty-free. These uses could include providing information to insurers, employers, and law enforcement agencies.
Facts Box 2:
Genetic counsellors
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- To become an accredited genetic counsellor, a Master’s degree in genetic counselling is required. This is currently not available in Singapore.
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- Following degree conferment, genetic counsellors can be certified, which enables them to take on more senior roles. Yasmin, for example, is a Fellow of the Human Genetics Society of Australasia.
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- Besides patients, genetic counsellors also provide genetics-related advice to doctors from the private sector. They explain which genetic tests are appropriate and what results mean, so that the doctors can better guide their own patients.