Prenatal diagnosis using interphase fluorescence in situ hybridization (FISH): 2-year multi-center retrospective study and review of the literature.

Since 1993, the position of the American College of Medical Genetics (ACMG) has been that prenatal interphase fluorescence in situ hybridization (FISH) is investigational. In 1997, the FDA cleared the AneuVysion assay (Vysis, Inc.) to enumerate chromosomes 13, 18, 21, X and Y for prenatal diagnosis. Data is presented from the clinical trial that led to regulatory clearance (1379 pregnancies) and from retrospective case review on 5197 new pregnancies. These studies demonstrated an extremely high concordance rate between FISH and standard cytogenetics (99.8%) for specific abnormalities that the AneuVysion assay is designed to detect. In 29 039 informative testing events (6576 new and 22 463 cases in the literature) only one false positive (false positive rate = 0.003%) and seven false negative results (false negative rate = 0.024%) occurred. A historical review of all known accounts of specimens tested is presented (29 039 using AneuVysion and 18 275 specimens tested with other probes). These performance characteristics support a prenatal management strategy that includes utilization of FISH for prenatal testing when a diagnosis of aneuploidy of chromosome 13, 18, 21, X or Y is highly suspected by virtue of maternal age, positive maternal serum biochemical screening or abnormal ultrasound findings.

Factors influencing health insurers' decisions to cover new genetic technologies.

OBJECTIVE: To examine the relative importance of factors influencing health insurers' coverage of new genetic technologies. METHODS: A national survey in which the decision makers for private health insurers were asked whether they would cover cystic fibrosis (CF) carrier screening, testing for genetic susceptibility to breast cancer (BRCA test), and medical costs of a clinical trial of gene therapy for CF under a variety of conditions. RESULTS: Respondents' coverage of the two tests and of medical costs of clinical trials was low at the time of the study (4%-15.5% of insurers). Their coverage of CF carrier screening and BRCA testing would be increased significantly if the group tested was restricted to those at high risk, if detection rates were higher and costs lower, and if testing was endorsed by a national professional group or consensus conference. Coverage of the medical costs of a trial of CF gene therapy would be significantly more likely if the trial was restricted to children or adults with severe CF, safety and effectiveness was proven, and therapy could be administered in a regional hospital or an outpatient setting rather than in a research hospital. CONCLUSIONS: Health insurers play a critical role in the diffusion of new genetic technologies. The validity of genetic tests and the safety and effectiveness of new therapies are primary factors influencing health insurers' coverage. Lower costs and approval of professional groups are other factors associated with increased coverage.

Constitutive and regulated expression of telomerase reverse transcriptase (hTERT) in human lymphocytes.

Human telomerase consists of two essential components, telomerase RNA template (hTER) and telomerase reverse transcriptase (hTERT), and functions to synthesize telomere repeats that serve to protect the integrity of chromosomes and to prolong the replicative life span of cells. Telomerase activity is expressed selectively in germ-line and malignant tumor cells but not in most normal human somatic cells. As a notable exception, telomerase is expressed in human lymphocytes during development, differentiation, and activation. Recent studies have suggested that regulation of telomerase is determined by transcription of hTERT but not hTER. The highly regulated expression of telomerase in lymphocytes provides an opportunity to analyze the contribution of transcriptional regulation of hTERT and hTER. We report here an analysis of hTERT expression by Northern and in situ hybridization. It was found that hTERT mRNA is expressed at detectable levels in all subsets of human lymphocytes isolated from thymus, tonsil, and peripheral blood, regardless of the status of telomerase activity. hTERT expression is regulated as a function of lineage development, differentiation, and activation. Strikingly, however, telomerase activity in these cells is not correlated strictly with the levels of hTERT and hTER transcripts. The absence of correlation between telomerase activity and hTERT mRNA could not be attributed to the presence of hTERT splice variants or to detectable inhibitors of telomerase activity. Thus, transcriptional regulation of hTERT is not sufficient to account for telomerase activity in human lymphocytes, indicating a likely role of posttranscriptional factors in the control of enzyme function.