ABSTRACT
Herein we report the result of a prospective study directly comparing aneuploidy detection of chromosome 21 by fluorescence in situ hybridisation in interphase nuclei with the results obtained by cytogenetic analysis.The inter-Alu sequences in chromosome 21 specific YAC clone were amplified by polymerase chain reaction [PCR]. The resulting DNA probe was used for fluorescence in situ suppression hybridisation to detect the copy numbers of chromosome 21 in interphase nuclei.A total of 214 independent amniotic fluid samples were analysed in a blind fashion. The combination of specific probe and optimized hybridisation and detection conditions allowed accurate enumeration of chromosome 21 in uncultured amniotic fluid cells consistent with the results obtained by traditional cytogenetic analysis