PRENATAL DETECTION OF CHROMOSOME ANEUPLOIDIES BY FLUORESCENCE IN-SITUHYBRIDIZATION - EXPERIENCE WITH 2000 UNCULTURED AMNIOTIC-FLUID SAMPLES IN A PROSPECTIVE PRECLINICAL TRIAL

Successful rapid prenatal detection of selected numerical chromosome a bnormalities by using fluorescence in situ hybridization (FISH) on unc ultured amniotic fluid samples has been described by Klinger el al. (1 992) and Ward et al. (1993, 1997). Using essentially the same FISH pro tocol and identical probes specific for chromosomes 21, 18, 13, X, and Y, we prospectively compared the results of FISH and conventional cyt ogenetics on 2000 amniotic fluid cell samples. The I-day FISH assay yi elded discrete differences in the signal profiles between cytogenetica lly disomic, i.e., normal, and trisomic samples. Due to intermittent a bsent Y-signals, the assay differentiated less well between samples wi th cytogenetically normal and abnormal sex chromosome complements. The assay efficiency, and thus the clinical utility, was affected by (1) unsuccessful hybridizations (7 per cent of all hybridizations), (2) hy bridizations with less than 50 scorable nuclei (19 per cent of all hyb ridizations), and (3) visibly contaminated samples with possible mater nal cell contamination (14 per cent of all samples). As a result, we w ere not able to reproduce the results of Klinger rt al. (1992) and War d er al. (1993, 1997). (C) 1997 by John Wiley & Sons, Ltd.