PubMed · 14827022
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R F van WERING. 1950. [Amniotic fluid emboli].. https://pubmed.ncbi.nlm.nih.gov/14827022/
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Complete and partial trisomies of chromosome 13 are characterized by abnormal fetal development and birth defects. Despite the severe abnormalities associated with trisomy 13, some couples elect not to undergo invasive prenatal diagnosis (PND) due to the 0.5%-1.0% risk of pregnancy loss. As a result, current studies are focusing on refining non-invasive prenatal diagnostic techniques, such as screening fetal cells isolated from maternal blood or cervical smears. As these techniques only provide a limited number of cells for analysis, any progress in this field depends on the development of a highly sensitive genetic screening strategy. We have developed a quantitative fluorescent PCR (QF-PCR) system capable of detecting chromosome 13 aneuploidy from as few as 10 cells. The system was further validated by screening 13 amniocyte samples, three of which had been diagnosed by FISH as having chromosomal abnormalities involving chromosome 13. In all cases, the QF-PCR results were concordant with those obtained using FISH. The high reliability (99%) and accuracy (96%) of the QF-PCR system at the 10 cell level makes this technique ideal for use in non-invasive PND.
Chromosomal mosaicism is one of the most vexing problems for clinical cytogenetic laboratories and personnel time used for analysis at the microscope is one of the principle costs in cytogenetic laboratories. We use data collected from 26 cytogenetic laboratories to evaluate whether the American College of Medical Genetics guidelines for minimum number of cells to count to exclude mosaicism in amniotic fluid specimens is appropriate. An accurate estimate of the number of mosaics that are missed by current cell counting practices is an important step in this process. Thus, we present a new method for estimating the number of mosaics that are missed and we use computer simulation to evaluate this new method. Our results indicate that if the clinical significance of mosaicism is suspected to be minimal for certain cytogenetic anomalies when the percentage of abnormal cells is 15 per cent or less, then it may be sufficient to use a 15-cell counting-rule-for-detection along with a minimum total cell count of 30 regardless of whether abnormal cells or normal cells are in the minority.
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