Rapid and simple prenatal diagnosis of common chromosome disorders: advantages and disadvantages of the molecular methods FISH and QF-PCR

Abstract

Molecular techniques have been developed for prenatal diagnosis of the most common chromosome disorders (trisomies 21, 13, 18 and sex chromosome aneuploidies) where results are available within a day or two. This involves fluorescence in situ hybridization (FISH) and microscopy analysis of fetal cells or quantitative fluorescence polymerase chain reaction (QF-PCR) on fetal DNA. Guidance is provided on the technological pitfalls in setting up and running these methods. Both methods are reliable, and the risk for misdiagnosis is low, although slightly higher for FISH. FISH is also more labour intensive than QF-PCR, the latter lending itself more easily to automation. These tests have been used as a preamble to full chromosome analysis by microscopy. However, there is a trend to apply the tests as 'stand-alone' tests for women who are at relatively low risk of having a baby with a chromosome disorder, in particular that associated with advanced age or results of maternal serum screening programmes. These women comprise the majority of those currently offered prenatal diagnosis with respect to fetal chromosome disorders and if introduced on a larger scale, the use of FISH and QF-PCR would lead to substantial economical savings. The implication, on the other hand, is that around one in 500 to one in 1000 cases with a mentally and/or physically disabling chromosome disorder would remain undiagnosed.

Rapid aneuploidy detection with multiplex ligation-dependent probe amplification: a prospective study of 4000 amniotic fluid samples

“…On the one hand, it has the obvious advantage of detecting a selection of structural chromosome defects, 1,7 but on the other hand it can also detect submicroscopic copy number variations from which the clinical significance is not known, like, for instance, in the TYMS gene, or ethically disputed like in the BRCA2 gene. This obviously leads to uncertainties in genetic counselling due to lack of knowledge of prenatal genotype -phenotype correlations as seen and anticipated with genomic microarrays.…”

“…Moreover, it has a major additional diagnostic value in the further characterization of chromosome anomalies found by karyotyping. 1 Furthermore, in the case of a male fetus, maternal cell contamination (MCC) in uncultured AF samples can be demonstrated. 2 -4 However, the technique is labor-intensive and not easily applicable to automatic handling of a large number of samples.…”

Brief communication (Original). Rapid diagnosis of trisomy 21 by relative gene copy using real-time quantitative polymerase chain reaction

“…Several methods in molecular genetics, such as interphase fluorescent in situ hybridization (FISH) and quantitative fluorescence polymerase chain reaction (QF-PCR) have been developed to overcome the disadvantages of the cytogenetic analysis [6][7][8][9][10]. Because these methods do not require a cell culture, they provide a more rapid diagnosis.…”

Amniocentesis results: investigation of anxiety. The ARIA trial

“…There are powerful economic arguments for replacing karyotyping with Rapid testing, particularly with PCR, 25,36 and this has already happened in some parts of the country. Others have urged caution, arguing that women's preferences must be taken into account before making such a major policy change.…”