What is genetic testing?

Genetic testing is an incredibly useful tool for identifying changes or mutations in DNA that could lead to genetic disease. 

What does genetic testing involve?

  • Genetic testing involves carrying out a range of tests on samples of DNA taken from blood, hair, skin, saliva, amniotic fluid (the fluid that surrounds the baby during pregnancy) and other tissues.
  • The DNA sample is then sent to the laboratory where scientists look for specific changes in the DNA to find and identify any genetic disorders.
  • The laboratory results are then sent in writing to the individual’s doctor or genetic counsellor so that they can discuss them with the patient.
  • There are currently more than 2,000 genetic tests in use and more are in development.

Why is genetic testing needed?

  • A genetic test is generally performed in a particular individual or family for a specific medical purpose.
  • There are a number of reasons why a genetic test may be called for, these include:
    • Pre-implantation genetic diagnosis (PGD): Screening an embryo for a genetic disease
    • Prenatal testing: finding a genetic disease in an unborn baby
    • Carrier testing: finding out if parents carry a genetic mutation that they could pass onto their future children
    • Predictive genetic testing: testing an adult for a 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
    • Diagnostic genetic testing: making a diagnosis in a patient that is showing symptoms of a known genetic disease
    • Pharmacogenetic testing: determining the best dose or type of medicine to give an individual patient based on their genetics.

The results

  • Before a person has a genetic test, it is considered essential that they understand the benefits and limitations of the tests, as well as the possible consequences of the results.
  • The results of genetic testing may bring with them the need to make important, life-changing decisions.
  • For example, if parents find they have a high chance of passing on a genetic condition to their children, they must decide whether or not they should try for a baby.
  • As a result, genetic testing goes hand-in-hand with genetic counselling, both before and after testing.
  • Genetic counselling:
    • helps prepare people for the potential outcomes of a genetic test
    • helps patients to understand the results once they receive them
    • gives patients the opportunity to talk through their concerns and make informed decisions about what their next steps are going to be.

Direct-to-consumer testing

  • More recently genetic tests have been made available over the internet for individuals wanting to know more about their genetics, ancestry and future health.
  • This type of genetic testing does not generally involve medical consultation or a genetic counsellor unless the individual seeks it out themselves.
  • The results from the test are generally substantially less predictive than medical genetic testing, and are given directly to the consumer.

This page was last updated on 2014-11-13