PRENATAL DETECTION OF ANEUPLOIDY BY DIRECTLY LABELED MULTICOLORED PROBES AND INTERPHASE FLUORESCENCE IN-SITU HYBRIDIZATION

Objective: To detect aneuploidy of chromosomes 13, 18, 21,, X, and Y w ith use of new, directly labeled, multicolored, commercially available DNA probes from interphase cells of amniotic fluid (AF)., Material an d Methods: The hybridization sites of the five probes were validated b y metaphase analysis, The fluorescence in situ hybridization (FISH) no rmal range was determined from a series of normal AF specimens and tes ted on a series of normal and abnormal specimens, Results: The hybridi zation efficiencies of the five probes were 100%. The mean AF interpha se disomic signal patterns for chromosomes 13, 18, 21, NS, and NY were 95.9%, 89.1%, 94.3%, 94.7%, and 98.7%, respectively. Of a total of 50 8 eases analyzed, 211 were aneuploid, All cases were correctly identif ied and no false results occurred (in comparison with karyotypic! anal ysis), although maternal cell contamination nas relatively common, Con clusion: Clinical screening for aneuploidy of chromosomes 13, 18, 21, X, and Y from interphase AF cells is possible with use of these probes and FISH, eases of maternal cell contamination and mosaicism necessit ate cautious interpretation, The FISH procedure is recommended for, sc reening of common aneuploidies, followed by a complete chromosome anal ysis to detect anomalies,.