Very early prenatal diagnosis on coelomic cells using quantitative fluorescent polymerase chain reaction

Quantitative fluorescent PCR (QF-PCR) has been shown to be an accurate assay for the rapid prenatal diagnosis of chromosome disorders. The extra-embryonic coelom develops during week 4 of gestation and it can be aspirated from the following week, making coelocentesis the earliest possible method of prenatal diagnosis after implantation. The possibility of using the QF-PCR assay performed on DNA extracted from cells present in the extra-embryonic coelom has been evaluated for the detection of aneuploidies. QF-PCR amplification using several markers for chromosomes X, Y, 21, 18 and 13 was successfully achieved on all 17 serial samples of exo-coelomic fluid (ECF), placental tissue and maternal blood. Multiplex analyses of maternal blood samples and chorionic tissues allowed the distinction of fetal from maternal patterns and, eventually, the identification of maternal contamination of the ECF samples. Prenatal detection of fetal gender was successful in all cases. When tested with autosomal primers, seven samples were found to contain exclusively fetal DNA. Eight samples contained small amounts of maternal DNA that did not interfere with the QF-PCR analysis. One fetus showed trisomy 13. QF-PCR requires very small volumes of sample compared with cell culture, suggesting that coelocentesis may prove useful for very early prenatal diagnosis.