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What are genetic disorders and when should I do DNA testing?

Updated: Feb 17

by Andrew Shuen MD PhD, FRCPC



The human genome is a complex set of instructions that directs our growth and development, and it is highly influential to the outcome of our health. In some instances, the genome can change, or mutate, in a whole or partial section of the DNA. This produces genetic disorders. Genetic disorders can be present in an individual from birth, or occur later in life due to environmental exposures such as cigarette smoke or other carcinogens.

Mutations can appear at the base pair of the DNA (i.e., the nucleotides that pair together to form the structure of the DNA), in larger sections, or even in entire chromosomes. When the DNA mutates, it can no longer carry out its normal function, producing genetic disorders, diseases, and neurodiversity.


Genetic disorders can be categorized under 3 headings:


Single Gene Disorders


Over 10,000 genetic disorders are caused by mutations in a single gene. This is known as a monogenic disorder because it is caused by a defect in one singular gene. Since only one is involved, these can be easily tracked through families, meaning the risk of inherited disease in later generations can be predicted.

Some examples of the more common genetic disorders in this category include sickle cell anemia– a disease in which the blood cells are unusually shaped, impacting the way that oxygen is carried to all parts of the body; cystic fibrosis– a disorder that causes the cells to produce thick and sticky mucus, sweat and digestive juices, causing severe damage to the organs and hemochromatosis- a disorder in which extra iron builds up in the body to harmful levels.

Chromosome Disorders


Chromosomal disorders result from a change in the number or structure of chromosomes. Some chromosome abnormalities are harmless; humans can survive with as many as four additional sex chromosomes and live normal life spans, albeit with some hormone replacement treatment. Others are associated with clinical disorders. The most severe and rare chromosome disorders are caused by the loss or gain of whole chromosomes, which can affect hundreds, or even thousands, of genes. These conditions are usually fatal.

An example of a chromosome disorder includes Down’s Syndrome, which results from an extra chromosome; Edwards Syndrome, caused by the presence of a third copy of chromosome 18 and Turner Syndrome, a condition affecting only females, resulting when one of the X chromosomes is missing or partially missing.


Multifactorial Disorders


Multifactorial disorders are caused by changes in multiple genes, caused by a complex interaction with environmental and lifestyle factors. Some are caused by an acquired genetic mutation from external influences such as cigarette smoke, carcinogens within polluted air or the fumes from dangerous chemical reactions. When multiple genes mutate, this can cause cancer, high blood pressure & cholesterol, arthritis, and Alzheimer’s.


When and How to Get Tested:


Deciding to undertake genetic testing is a tremendously personal, but potentially life saving decision. There are a number of reasons why it may be necessary, for example:


1. Preimplantation genetic diagnosis (PGD): This is a common medical procedure performed during in vitro fertilization (IVF) that screens an embryo for a genetic disease.

2. Carrier testing: This aims to find out whether a parents carry a genetic mutation that they could pass onto their future children.

3. Predictive genetic testing: This tests an adult for genetic disease before they have symptoms, usually where the disease runs in the family, and they want to find out if they may also be affected.

4. Diagnostic genetic testing: makes a diagnosis in a patient that is showing symptoms of a known genetic disease.

5. Pharmacogenetics testing: determines the best dose or type of medicine to give an individual patient based on their genetics.


The result of genetic testing can be hugely beneficial, aiding individuals in their journey to making life-changing decisions about their health, lifestyle, fitness, nutrition and diet, medications, and treatment plans. This often goes hand-in-hand with counselling and advice from genomics experts. Genetic testing is available for newborns, children, and adults.


At Progenics Cord Blood Cryobank, we’re proud to offer an extensive panel of reports via a non-invasive Whole Genome Sequencing test in partnership with Genaissance lead by Dr Andrew Shuen, a board certified medical geneticist in Ontario. His clinic also offers support in the form of nutritional, medical or lifestyle advice that is tailored to each of your unique needs. Discover a world of information about your DNA and manage the future of your health, with genetic testing. Book a free 15-min initial consultation with him at https://rocketdoctor.ca/genaissance/ to learn more.



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