Genetic testing is the laboratory analysis of human genetic material including chromosomes, deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) to detect genetic material and/or identify genetic changes. As discussed in the section on “Basics”, chromosomes are composed of DNA. Specific DNA segments called genes serve as templates to make (transcribe) RNA. Genetic changes are referred to as “variations” or “variants” (sometimes called “mutations”).and they can have many different effects on the body. While most genetic variations do not affect a person’s health, they are sometimes related to disease.
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How is genetic testing done?
To test genetic material for medical reasons, some type of sample from the body is required. This sample can be blood, urine, saliva, body tissues, bone marrow, hair, etc. The material can be submitted in a tube, on a swab, in a container, or frozen. Once received in the laboratory, the genetic material is separated and removed from the sample.
Some genetic disorders are linked to a single gene, and genetic testing has traditionally focused on testing for mutations in genes based on a person’s symptoms or family history. For instance, cystic fibrosis has a well-defined set of symptoms and testing for mutations in one gene can usually identify the cause of those symptoms.
However, there are many other genetic disorders that are not so easily identified. These are linked to multiple genes or large sections of the genome. The ongoing development of new gene sequencing technology and the declining cost of sequencing has led to the development of tests that can look for genetic disorders beyond a single gene. The following sections provide an overview of genetic testing methods that range from detecting or examining a single gene to the whole genome.