MOLECULAR EVIDENCE OF FETAL-DERIVED CHROMOSOME-21 MARKERS (STRS) IN TRANSCERVICAL SAMPLES

Transcervical cells (TCCs), collected by flushing or aspiration at 8-1 3 weeks of gestation, were analysed for the presence of fetal-derived DNA sequences. DNA extracted from maternal peripheral blood, TCC sampl es, and placental tissue was amplified by the polymerase chain reactio n (PCR) to detect small tandem repeat (STR) markers specific to chromo some 21. STR products of fetal origin could be clearly observed in fou r TCC samples. TCC samples collected by flushing or aspiration were al so analysed by fluorescent in situ hybridization (FISH) using X and Y probes simultaneously: 46,XY cells could be detected in all TCC sample s obtained from mothers with male fetuses.