Screening for single gene genetic disease.

The screening and directed testing for genetic disease caused by single gene mutations is an expanding part of the overall scheme of prenatal care. In addition to reproductive choice, carrier screening and fetal diagnostic testing afford the important opportunity for preparation of the family and the delivery site for the birth of a fetus with a known genetic disorder. Increasingly the primary care provider in pregnancy bears the burden of engaging patients in discussions regarding available genetic tests appropriate to their family or personal history, their ethnic group, and with every patient for a limited but growing number of diseases. Ethnic-based risk identification and testing has expanded recently with, for example, the addition of familial dysautonomia for patients of Askhenazi ancestry. Widespread, or nearly universal, screening has emerged for cystic fibrosis and new initiatives are gaining momentum for prenatal maternal carrier screening for fragile X syndrome. The fruits of the human genome project will undoubtedly lead to the identification of more genes that underlie human disease. This will expand the menu of possible prenatal testing options and will raise the level of complexity in both counseling, testing logisitics and health care resource allocation.