Rapid prenatal diagnosis of aneuploidy by quantitative fluorescent PCR on fetal samples from mothers at high risk for chromosome disorders

We report the results of a prospective study using quantitative fluorescent polymerase chain reaction (OF-PCR) and small tandem repeat markers (STR) for the rapid prenatal detection of aneuploidies in a group of pregnant women at increased risk of having fetuses with numerical chromosome disorders. Amniotic fluid samples (n = 52) were collected from mothers undergoing prenatal invasive testing for fetal abnormalities on ultrasonographic examination or abnormal maternal serum aneuploidy screening results. All samples were tested by cytogenetic analysis, but rapid diagnoses of aneuploidies were offered and performed using QF-PCR analysis with several STRs specific for chromosomes 21, 18, 13 and X. All cases with numerical chromosome aberrations involving chromosomes 21, 18 and 13 (n 8) were correctly diagnosed. Three gonosomal aneuplodies (one 47,XXY and two 45,X) were not detected because they were uninformative for the X markers. Another sample with a deletion (46,XX,7q-), that the present assay was not designed to detect, was not identified. One sample was heavily contaminated with maternal blood and the results of the OF-PCR assays were uninformative. The remaining samples from normal fetuses provided OF-PCR patterns disomic for chromosomes 21, 18, 13 and X. Our study demonstrates that OF-PCR is a rapid method for the detection of common numerical chromosome disorders and it may play an important role in prenatal diagnosis for women at high risk for fetal aneuploidy.