Molecular geneticists studying an autoradiograph.

Molecular geneticists studying an autoradiograph of DNA results, Great Ormond Street Hospital, London, May 2000. Genetic testing is usually offered to people with a relative affected with a genetic condition. Genetic tests on a small blood sample can show who is an unaffected carrier of some recesive conditions (like cystic fibrosis) or who is likely to develop a condition in later life (like Huntingdon disease). Testing a foetus before birth can be offered to couples with a high risk of having a child with a serious genetic condition.