Advances in genetic analysis and the rise of direct-to-consumer DNA tests have changed the way we think about genetic testing. Now more than ever, patients and consumers can learn about their own genetic material. How can we — both as individuals and as larger communities — benefit from genetic testing?
1. Detect birth defects in utero
Every parent hopes to welcome a healthy child into the world. The nine month gestation period — albeit with ultrasounds and regular doctor checkups — is a nerve-wrecking time for parents to be.
Prenatal genetic testing can identify some genetic disorders in utero, and is recommended for parents carrying recessive genes for conditions and mothers at risk from chromosomal abnormalities. Early identification of genetic disorders allow parents to better prepare for a special needs child or choose to terminate the pregnancy.
2. Identify genetic conditions at birth
The unfortunate reality of many genetic conditions is that they can never be cured, only controlled. However, early intervention is key to improved health outcomes and reducing disorder severity. In the United States, over 95% of babies are tested for a whole range of genetic diseases — about 3000 (out of over 4 million) test positive and can begin early treatment.
3. Guide family planning decisions
Some of the deadliest genetic disorders — cystic fibrosis, Huntington’s disease and Tay-Sachs, among others — are caused by recessive genes. Healthy adults who have never experienced symptoms can nevertheless carry the gene without ever being aware.
When two carriers have a baby, the child has a 25% chance of developing the full disorder. This is a particular risk in insular communities who tend to intermarry — there are genetic testing programs directed towards Ashkenazi Jews and the Amish for this reason. With the results from these tests, carriers can make informed decisions about who to marry and who to have children with.
4. Reveal risk from genetic factors
When genetic disorders are controlled by a single gene, identification of carriers and affected individuals is relatively simple to test for. Humanity’s deadliest killers — cancer, heart disease, diabetes — are made up of a constellation of risk factors that are still not fully understood.
Advances in genetic testing allow you to know if you are at a greater risk from these diseases later in life, and how severely you may be affected. Additionally, identifying a genetic risk factor in one member of a family can prompt close family members to undergo genetic analysis and evaluate their own levels of risk.
5. Understand family history
The primary purpose of genetic testing has, for years, been medical. Now, people are taking matters into their own hands. Direct-to-consumer ancestry testing has seen meteoric growth — more people analyzed their DNA with such a test in 2017 than in all previous years combined.
The ability to analyze and own your personal genetic data is evidently a tempting proposition. But as companies collect ever larger quantities of DNA, the question of who owns this data and what happens to it after testing is ever present. In June 2018, email addresses and password information associated with over 90 million users of genealogy website MyHeritage were exposed during a hacking incident. Luckily, MyHeritage store DNA data on a separate system protected by extra layers of security.
6. Reach historically underrepresented groups
Historically, medical research has focused on one subset of the population — white males. Non-white ethnicities and women have been underrepresented in initial research as well as pre-clinical and clinical trials. There are known differences between the sexes in symptoms, risk factors and outcomes for a whole host of diseases — cardiovascular disease, stroke and asthma, to name a few.
This narrow focus results in adverse treatment effects and population-specific genetic disorders being overlooked. The availability and reach of direct-to-consumer genetic testing means future medical research has the potential to be far more inclusive and precise.
7. Personalize medical treatment
If one size fits all doesn’t apply to clothes, how could it possibly apply to medicine? Our previous point highlighted how different population groups respond differently to treatment — genetic testing goes even further by personalizing treatment to specific individuals.
Genetic factors can significantly affect the body’s response to drugs — the study of this field is known as pharmacogenomics. For example, Abacavir is a highly effective treatment option for most HIV sufferers, however causes severe side effects for 5–12% of the patients. Patients with the HLA-B*5701 gene variant were found to be most likely to suffer these side effects. By screening for this gene variant, another treatment option could be offered to these patients.
This personalization could even reduce the need for one of the most gruelling treatments of all — chemotherapy. A major international study recently found that some women with early-stage breast cancer could skip chemotherapy altogether, as long as their tumor showed specific genetic markers. Breast cancer tumors with these genetic markers can be treated solely using estrogen blockers.
8. Contribute to drug and treatment research
Millions more people undergoing genetic testing mean a potentially enormous sample pool for genetic research. More data available offers opportunities to identify new genes, better understand genetic conditions and formulate new drugs and treatment options.
Medical genetic testing has strict conduct codes around sample acquisition and informed consent of its subjects. The largest direct-to-consumer genetic tests share sequence data with non-profits and research institutions and other, for-profit parties — the data is used to develop new treatments that can help millions (and make millions). However, the individuals who supply the data do not benefit from these profits and can’t know if their samples have been used.
9. Relief from uncertainty
Knowing that you or your children may be at risk from a genetic condition is a deeply stressful experience. Many people affected report the feeling of “waiting for the other shoe to drop”, especially for conditions where symptoms typically appear late in life.
Undergoing a genetic test and receiving clear information can give great relief from this uncertainty. A negative diagnosis rules out the disease completely, while positive diagnoses can be used to undergo checkups more frequently and take steps for early intervention.
10. Make informed decisions
Knowledge is power. Whether prenatal, in early childhood or as an adult, knowing the level of risk is key towards directing future decisions. A person who undergoes genetic testing and discovers a predisposition towards skin cancer can take greater care to stay out of the sun, while someone predisposed towards Type 2 diabetes can preemptively make healthier diet choices. People with a predisposition to Alzheimer’s disease can slow the onset of symptoms through diet and taking up certain hobbies. Clear information means factors under the patient’s control can be identified and improved.
In an ideal case scenario, genetic testing should take place in conjunction with genomic counseling. The potential psychological effects — feelings of dread or hopelessness — of a poor diagnosis — should not be discounted. For most patients, however, the benefits of early intervention, improved treatment outcomes and increased sense of control far outweigh the negatives.
While the benefits to individuals are mostly positive, the collection of large amounts of genetic data raises questions about privacy, data protection and potential genetic discrimination. Will regulations that protect the individual keep pace with this new technology? That remains to be seen.