There are several types of genetic tests, some that test a small number of genes and others that examine the genome on a large scale (Genetic Testing | CDC, 2022). Each type has its pros and cons, and deciding which test will provide the best results may be difficult for medical professionals. This decision may rest on the patient’s family history or exposure to known mutagens, substances that change the DNA.

Small-scale genetic tests are either single-gene tests or panel tests, where a small amount of genes are sequenced and compared. In a single-gene test, only one gene is examined for mutations. A panel test examines a small amount of genes known to have a significant impact on an individual’s health. These types of tests are often chosen from a pre-made set based on the patient’s symptoms and family history, to confirm a specific diagnosis where a limited amount of genes are involved.

On the other hand, large-scale tests examine the genome in search of multiple genetic mutations that may intersect to cause a genetic disorder. The genome sequencing test is recommended when faced with a complex medical history, as it can identify thousands of health conditions caused by genetic mutations. The exome sequencing test should be performed when a medical professional believes the genetic disorder may be rare and that a genome sequencing test will not identify the disorder.

The use of LSGT can identify over 6000 different medical disorders (Online Mendelian Inheritance in Man, 2023; Costain et al., 2021).  LSGT can be used to identify your, or your familial, risks of:

• Certain types of cancers
• Familial hypertension
• Familial hypercholesterolemia: The body is unable to process cholesterol, leading to a patient being at a higher risk of cardiovascular disease.
• Diabetes
• Multiple sclerosis
• Alzheimer’s disease
• Parkinson’s disease
• Autism

It can also be used to diagnose:

Cystic fibrosis: A disorder that affects the body’s ability to produce mucus, digestive fluids, and sweat. This can lead to severe damage to the lungs, stomach, pancreas, and other organs.
Duchenne muscular dystrophy: A type of muscle dystrophy that primarily affects young boys beginning around the age of 4. This disorder may also affect the brain and cause some intellectual disability (Venugopal & Pavlakis, 2023).
Hemophilia A: A disorder in which the body has low or none of the clotting factors that cause the blood to coagulate after an injury. Individuals with this disorder may bleed profusely from the smallest of cuts.
Marfan syndrome: A disorder that affects the connective tissue, such as ligaments and cartilage, that help support your body. It can be severe if the heart becomes affected by this disorder.
Multiple endocrine neoplasias: A genetic disorder that causes tumors and/or cancers in the endocrine system.

This is not an exhaustive list of congenital risks or disorders that may be identified by an LSGT. Your medical team will identify which type of LSGT is best suited to identify the cause of your symptoms or may order both tests.

The use of LSGT in medicine has become more prevalent as more research has been conducted and the process has improved (Garavito et al., 2022). These improvements have made LSGT to be a cost-effective way to help identify risk factors for health disorders and allow for preventative measures to be suggested for each individual. Since LSGT can also be used to identify how a person may react to different medications, a test known as a pharmacogenetic test, it is even possible for a medical team to ensure that any prescribed medications will be the most effective while having the least amount of side effects.

Few countries have added genetic testing to their health insurance coverage; however, there is a growing push to do so. Providing genetic testing to patients would allow for more personalized preventative care, which in turn would reduce the overall costs to a health system. This is especially true when it comes to pharmacogenetic tests.

Pharmacogenetic testing examines the way an individual metabolizes different medical compounds (Hockings et al., 2020). By identifying which medication will provide the best results with the fewest side effects, medical teams, and patients would be able to skip the current trial-and-error approach involved in addressing complex medical needs, such as long-term pain management, or more delicate ones, such as mental health medications.

Ontario has added genetic testing to the services covered by OHIP as part of a trial program. OHIP will cover LSGT if a patient meets specific requirements as determined by a member of an approved genetic clinic.

There are a few risks associated with taking an LSGT. The procedure to gather the DNA sample is straightforward and often routine for qualified medical professionals.

The most common side effect of a genetic test is anxiety, either while waiting for the results or after receiving them, due to the possibility of severe future health risks being identified. As such, it is recommended that any genetic test be accompanied by genetic counseling with a qualified medical professional. This professional will be able to explain the results of the test and work with the medical team to create a prevention or treatment plan for any identified high-risk health issues.

The Wilderman Medical Clinic offers specialized genetic testing, including tests for:

• Cancer
• Cardiovascular diseases
• Pharmacogenetics
• Pregnancy and prenatal testing
• Proactive wellness testing

Please, contact the clinic for more information.

Costain, G., Cohn, R. D., Scherer, S. W., & Marshall, C. R. (2021). Genome sequencing as a diagnostic test. Canadian Medical Association Journal, 193(42), E1626–E1629. https://doi.org/10.1503/cmaj.210549

Durmaz, A., Karaca, E., Demkow, U., Toruner, G., Schoumans, J., & Çoğulu, Ö. (2015). Evolution of genetic techniques: past, present, and beyond. BioMed Research International, 2015, 1–7. https://doi.org/10.1155/2015/461524

Franceschini, N., Frick, A., & Kopp, J. B. (2018). Genetic testing in clinical settings. American Journal of Kidney Diseases, 72(4), 569–581. https://doi.org/10.1053/j.ajkd.2018.02.351

Garavito, G. a. A., Moniz, T., Deom, N., Redin, F., Pichini, A., & Vindrola‐Padros, C. (2022). The implementation of large-scale genomic screening or diagnostic programmes: A rapid evidence review. European Journal of Human Genetics, 31(3), 282–295. https://doi.org/10.1038/s41431-022-01259-8

Genetic testing | CDC. (2022, June 24). https://www.cdc.gov/genomics/gtesting/genetic_testing.htm

Hockings, J., Pasternak, A. L., Erwin, A., Mason, N., Eng, C., & Hicks, J. K. (2020). Pharmacogenomics: An evolving clinical tool for precision medicine. Cleveland Clinic Journal of Medicine, 87(2), 91–99. https://doi.org/10.3949/ccjm.87a.19073

Medline Plus. (2021, July 28). What are whole exome sequencing and whole genome sequencing?: MedlinePlus Genetics. MedlinePlus. https://medlineplus.gov/genetics/understanding/testing/sequencing/

National Human Genome Research Institute. (2023, October 3). Exome. Genome.gov. https://www.genome.gov/genetics-glossary/Exome

Online Mendelian Inheritance in Man. (2023, October 4). GeneMap – OMIM. https://www.omim.org/statistics/geneMap