PRENATAL-DIAGNOSIS BY FLUORESCENCE IN-SITU HYBRIDIZATION ON CHORIONICVILLUS CELLS - NONSIGNIFICANCE OF MATERNAL CELL CONTAMINATION

We assessed the effect of maternal cell contamination on the sensitivi ty of prenatal diagnosis by fluorescence in situ hybridization (FISH) on overnight attached mesenchymal chorionic villus cells. Double targe ts FISHs with X and Y chromosome-specific probes were performed on par allel samples from the same pregnancies: (1) samples of assumed fetal tissue retained during dissection, and (2) samples of suspected matern al tissue discarded during dissection. In the karyotypically male samp les the tissue retained during dissection contained 0-3% nuclei with t wo X-specific signals each. In the tissue discarded from the karyotypi cally male samples 0-50% of the nuclei had two X-specific signals each . We conclude that given thorough dissection of chorionic villi, the s ensitivity of prenatal diagnosis of aneuploidies by FISH on overnight attached samples of this tissue is not critically affected by maternal cell contamination.