Tay-Sachs disease--carrier screening, prenatal diagnosis, and the molecular era. An international perspective, 1970 to 1993. The International TSD Data Collection Network.
OBJECTIVES: To provide an update of the international experience with carrier screening and prenatal diagnosis for Tay-Sachs disease (TSD), to assess the impact of these efforts, and to review the recent developments in DNA technology with application to TSD carrier detection and screening. DESIGN: Through the International TSD Testing, Quality Control, and Data Collection Center, all testing centers in the world were surveyed annually to assess overall experience with carrier testing and prenatal diagnosis. Quality control and laboratory surveillance of testing centers were performed through an annual assessment, using samples provided by the center. SETTING: Tay-Sachs disease testing centers around the world. PARTICIPANTS: Nearly 1 million young adults from both Jewish and non-Jewish populations. INTERVENTION: Gene product screening (enzyme testing) and DNA-based mutation analysis (in some populations). MAIN OUTCOME MEASURE: Impact of screening program on disease incidence. RESULTS: Data from all centers in the international TSD network on experience with TSD carrier testing and prenatal diagnosis since 1974 indicated that more than 36,000 heterozygotes were identified and 1056 couples found to be at risk for TSD in their offspring. A total of 2416 pregnancies at increased risk for TSD were monitored by amniocentesis or chorionic villus sampling. A dramatic decrease in the incidence of TSD in the Jewish populations was demonstrated. With both serum and leukocyte proficiency testing, there have been only 16 instances (of 845 cumulative laboratory evaluations) of one or more errors reported by a laboratory since 1983 resulting in nonaccreditation. CONCLUSIONS: This analysis represents a prototypic effort in coordinating adult education, carrier testing, and genetic counseling directed toward prospective prevention of a uniformly fatal childhood disease and demonstrates that such an effort can dramatically affect disease incidence.