ABSTRACT
This chapter describes the basic genetic mechanisms and provides relevant information to help identify patients with, or at risk of, a genetic condition, so that they can be counselled appropriately. Genetic factors are known to contribute to the majority of human diseases, so information about an individual’s genetic make-up may be important to their clinical care and that of their family. Genetic tests may be used to detect, confirm or rule out a genetic condition. During pregnancy these tests provide parents with information so that they may avoid the birth of a baby with a serious genetic condition, or it may start discussions about coping with a child with that condition. In multifactorial inheritance, a condition occurs as the result of a combination of environmental factors such as obesity or smoking, and numerous genetic factors. Referral to the clinical genetics service is essential, but it may be difficult to provide a clear prognosis.
