Rapid prenatal diagnosis of Down's syndrome in the first trimester of pregnancy by fluorescence in situ hybridization

OBJECTIVE: To assess whether fluorescence in situ hybridization (FISH) with chromosome 21, specific DNA probe is applicable as a prenatal diagnostic tool for Down's syndrome. METHOD: We used FISH with chromosome 21 specific probe on 30 uncultured chorionic villi cell samples to detect the Down's fetus, and we also performed the conventional chromosome analysis of chorion cells from parallel samples. RESULTS: In samples with disomic karyotype, an average of 1 percent (0-5 percent) of the nuclei had three hybridization signals. By contrast, in the samples of trisomy 21 fetus, an average of 86 percent (78-91 percent) of the nuclei displayed three signals. CONCLUSION: FISH can provide a rapid and accurate method for the first trimester prenatal diagnosis of Down's syndrome.