It's helpful to families being evaluated for predisposition to hereditary cancers to have a basic knowledge of the terminology they will hear. This list of genetic terms will introduce you to important concepts you will encounter, from identification of a genetic defect through counseling, treatment and follow up.
Every individual has a large amount of genetic information that is organized into smaller segments known as “genes.” Genes provide the necessary instructions that our cells require to perform their different functions within our bodies. With rare exceptions, each person has two copies of every gene. Most genetic conditions occur when the composition of one or both copies of a specific gene are altered (also known as “mutated”).
Genetic tests are laboratory studies that identify whether an individual has a genetic disorder. Although many techniques can be used as part of the testing process, in general genetic testing involves the isolation of DNA from a sample of blood or other tissue obtained from an individual undergoing testing. Subsequently, the two copies of a specific gene are evaluated and compared to a “normal” reference code. If an alteration (also known as a “mutation”) is identified, it is often possible to determine whether this alteration has been previously reported in other individuals with similar features. This information could strengthen the conclusion that the individual being tested has the genetic disorder for which he or she is being tested.
Genetic tests may be used for many purposes, including the diagnosis of a genetic disease in newborns, children and adults; the identification of future health risks; the prediction of drug and treatment responses; and the assessment of risks to future children.
Genetic counseling is the process of explaining the basic principles of genetics and genetic testing to individuals, couples or families. Genetic counselors help patients understand why genetic tests are performed and how the results of the genetic test might impact their physical and/or psychological well-being. Genetic counselors also assist their clients by translating scientific genetic knowledge into practical information so individuals or families can understanding the genetic concepts that apply to them and can make informed decisions about testing and medical care.
Hereditary cancer predisposition is the cancer risk for an individual who carries an alteration in a specific gene known to be associated with a particular type of cancer(s). As a result of having this genetic alteration, he or she is at an increased risk to develop cancer(s) when compared to someone in the general population who does not have an alteration in the same gene. Affected individuals commonly develop cancer at earlier than expected ages and may also have relatives with similar or other types of cancer (also known as a “positive family history” of cancer). Because individuals who carry a cancer predisposing gene mutation can pass the alteration on to a proportion of their future children, cancer predisposing conditions are often considered “hereditary."
Cancer surveillance is the process of completing screening examinations, or medical tests, when an individual with a cancer predisposing condition has no symptoms of cancer. These tests help ensure that cancers are detected at their earliest and most treatable stages. Individuals who have already completed cancer treatment typically undergo additional surveillance after treatment is done to monitor for the possible recurrence of their cancer. Examples of cancer surveillance measures include physical examinations, blood tests and certain radiology studies.