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

Abstract

We report the results of a prospective study using quantitative fluorescent polymerase chain reaction (QF-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 QF-PCR assays were uninformative. The remaining samples from normal fetuses provided QF-PCR patterns disomic for chromosomes 21, 18, 13 and X. Our study demonstrates that QF-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.

Prenatal Screening for Aneuploidies by Quantitative Fluorescent Polymerase Chain Reaction

“…As suggested by Pertl et al [10], QF-PCR should be used to test all samples retrieved from mothers suspected of being at high risk for chromosome disorders in view of previous non-invasive biochemical or ultrasound results.…”

“…A large number of chromosome-specific nucleotide repeats are now available (table 1), and so far, several thousand amniotic or chorionic samples have been investigated either in the course of experimental studies or during large clinical trials [6, 7, 8, 9, 10, 11, 26, 27]. In three investigations, about 6,000 amniotic and chorionic samples have been tested sequentially without detecting false or negative results [27][Maredith, R., pers.…”

“…Only one false result was recorded, due to mishandling of the specimen during postal transfer across three laboratories. In a recent study, Pertl et al [10]assessed the diagnostic value of performing rapid prenatal diagnosis of chromosome disorders by QF-PCR on a group of pregnant women at increased risk of having affected fetuses according to previously performed biochemical or ultrasound tests. All cases with numerical aberrations involving chromosomes 21, 18 and 13 were correctly detected with no false-positive results.…”

“…An alternative approach is to employ a quantitative fluorescent polymerase chain reaction (QF-PCR) assay that allows the detection of major numerical chromosome disorders in the space of a few hours after the collection of the samples [5, 6, 7, 8, 9, 10, 11]. The principle of this method is based on the PCR amplification of selected short tandem repeats (STRs) which, as implied by the name, are small nucleotide motifs reiterated several times to form DNA sequences of different lengths [12, 13, 14].…”

“…The QF-PCR assay is particularly useful for investigating pregnant women suspected, by previous non-invasive analyses such as ultrasound or biochemical screening tests, to carry affected fetuses [10]. …”