Best practices: antenatal screening for common genetic conditions other than aneuploidy

Abstract

Carrier screening aims to identify asymptomatic heterozygotes of heritable disorders and has a vital, ever-changing role in its application to the prenatal detection of disease. An explosion of new technologies for the identification of single-gene disorders challenges our ability to evaluate each individual test prior to its introduction into the private and public sectors. The efficacy of carrier screening is dependent on several factors including the validity of the test, the incidence of disease within the community, and as many genetic disorders segregate along ethnic and racial lines, which populations should be offered testing. The difficulties in evaluating prenatal screening programs are highlighted by the recent conflicting recommendations from the American College of Medical Genetics and the American Congress of Obstetrics and Gynecology over several single-gene disorders. In addition, changes in the recommendation for universal versus risk-based screening for ethnically segregated disorders remain controversial. These conflicts have major impacts in the provision of genetic counseling in the prenatal outpatient setting. We will evaluate current and proposed screening protocols for several single-gene disorders, and comment on universal versus ethnic-based screening. Our objective is to develop guidelines for genetic screening in the antenatal outpatient setting.