2.17—Genetic screening uses and implications

Genetic screening tests DNA to identify a carrier, assess an embryo before implantation, or test a foetus during pregnancy. It informs a decision; it does not by itself predict every aspect of a person's future health.

Carrier testing checks an asymptomatic person's allele status. Pre-implantation genetic diagnosis analyses embryo cells during IVF before implantation. Prenatal testing uses chorionic villus sampling or amniocentesis to obtain foetal DNA during pregnancy.

Chorionic villus sampling is earlier than amniocentesis, while both can provide information about a familial disorder. A result may help parents prepare or consider options, but sampling carries procedure risks and tests can give false results.

Keep the test, the probability and the decision separate: a positive screen is not a guarantee of disease severity, and a negative result is not proof that no health problem exists. Genetic counselling helps interpret uncertainty.