Detection of fetal aneuploidies by QF-PCR in transcervical cell samples

OBJECTIVE: To evaluate the accuracy in the diagnosis of aneuploidies of a quantitative fluorescent polymerase chain reaction (QF-PCR) assay on trophoblastic cells recovered from transcervical cells samples (TCCs) collected by intrauterine lavage (IUL). STUDY DESIGN: We analysed three IUL samples collected prior to first trimester termination of pregnancy, requested for increased aneuploidy risk following nuchal translucency measurement. IUL was performed using a flexible catheter attached to a syringe filled with 10 ml of saline solution, gently flushed through the cervical canal, just past the internal os, and then aspirated back. We performed a DNA analysis on cells of seemingly trophoblastic origin isolated from IUL samples, after micromanipulation under inverted microscope. The analysis was performed by multiplex QF-PCR, including short tandem repeats (STRs) for the chromosomes X, Y, 21, 13, and 18 (a panel of as many as 29 polymorphic STRs was used). The same QF-PCR reaction was performed in the corresponding placental tissue samples to confirm the trophoblastic origin of the specimen and in the maternal blood for comparison. RESULTS: The QF-PCR analysis on placental samples revealed that among the three cases studied there were two cases of trisomy 21 and one case of monosomy X; the comparison of peak profiles obtained from IUL, placental and maternal samples confirmed the diagnosis of aneuplody and also the trophoblastic origin of the cells isolated from IUL samples, in all three cases. CONCLUSION: This study suggests that the detection of chromosomal aneuploidies in micromanipulated TCC samples can be achieved by QF-PCR amplifi- cation of selected highly polymorphic and chromosome specific markers. With respect to standard karyotype, QF-PCR analysis has the limitation that only numerical abnormalities of selected chromosomes can be detected, but retains the advantage of being quicker, less expensive and less lab-demanding