A simple method for prenatal diagnosis of trisomy 21 on uncultured amniocytes.

Prenatal diagnosis of trisomy 21 would be easier if fluorescence in situ hybridization (FISH) could be applied to interphase nuclei. Therefore, we prepared a chromosome-21-specific probe by in vitro enzymatic amplification of inter-Alu sequences from YAC clones previously localized to this chromosome. This probe was used for FISH on 22 uncultured amniocyte samples. An easy, rapid, and safe technique is proposed for the prenatal diagnosis of trisomy 21.