Rapid detection of numerical aberrations of chromosomes in the first trimester of pregnancy by using fluorescence in situ hybridization (FISH)

: Fluorescence in situ hybridization (FISH) has been applied for rapid prenatal diagnosis of common numerical aberrations of chromosomes. We used FISH with chromosome 13, 18 and 21 specific probes on 528 uncultured mesenchymal chorionic villi cell samples to detect the chromosomal abnormalities, and we also performed the conventional chromosome analysis of cultured cells from parallel samples. The results showed, in samples disomic with respect to the probed chromosomes, and average of 1 percent (range 0-18 percent) had three hybridization signals. By contrast, in the samples trisomic or triploidic for the probed chromosomes, an average of 70 percent (52-84 percent) (chromosome 13), 73 percent (68-84 percent) (chromosome 18), and 76 percent (54-90 percent) (chromosome 21, including one case of mosaic trisomy 21) of the nuclei displayed three signals. The whole test took about 24 hours. We concluded that FISH can provide a rapid and accurate method for the first trimester prenatal idetification of selected numerical aberrations of chromosomes.