124
RENATE ULMER
Criteria for interpretation (in accordance with Eiben et al., 1998):
- in cases where <10% aneuploid signals are observed, euploidy is assumed.
- whenever >60% aneuploid signals are found, a case is classified as aneuploid.
- If 10-60% aneuploid signals are obtained, the case should be studied
intensively by further cytogenetic analyses. Such a result could indicate
mosaicism. In these cases more than 100 nuclei should be scored.
Maternal cell contamination (MCC): In amniotic fluid samples which are
bloody or brownish, a high percentage of MCC can be expected (in bloody
fluids we found up to 82 % maternal cells). False negative results are possible. We did not find clear morphological differences between maternal
and fetal interphase nuclei (except in same cases). Winsor et al.(1996)
found a rate of maternal cell contamination (MCC) in uncultured amniotic fluids, which is much higher than expected with cultured fluid. They
identified MCC in 1071500 (21.4%) uncultured interphase nuclei using X
and Y FISH probes, compared with 11500 (0.2%) in metaphases after cell
culture. Winsor mentioned that it is not always possible to differentiate
between maternal and fetal cells based on nuclear morphology. Although
they found it likely that most of the multi-lobulated nuclei are segmented
neutrophils from maternal blood, lobulated nuclei may also be fetal.
Specimens containing blood should therefore be excluded from analysis or the result should only be given if there are signals with a male
constellation.
Acknowledgements. Thanks are extended to Dr. Anita Rauch and Dr. Udo Trautmann for
helpful advice, to Michaela Kirsch and Anja Kollert for their advice and technical assistance
and Dr. Thomas Liehr for critically reading the manuscript.
References
BryndorfT, Christensen B, Vad M, Pamer J, Brocks V, Philip J (1997) Prenatal detection of chromosome aneuploidies by fluorescence in situ hybridization: experience
with 2000 uncultured amniotic fluid samples in a prospective preclinical trial. Prenat
Diagn 17:4,333-341
Claussen U, Ulmer R, Beinder E, Voigt H-J (1994) Six years experience with rapid karyotyping in prenatal diagnosis: correlations between phenotype detected by ultrasound and fetal karyotype. Prenat Diagn 14:113-121
RENATE ULMER
Criteria for interpretation (in accordance with Eiben et al., 1998):
- in cases where <10% aneuploid signals are observed, euploidy is assumed.
- whenever >60% aneuploid signals are found, a case is classified as aneuploid.
- If 10-60% aneuploid signals are obtained, the case should be studied
intensively by further cytogenetic analyses. Such a result could indicate
mosaicism. In these cases more than 100 nuclei should be scored.
Maternal cell contamination (MCC): In amniotic fluid samples which are
bloody or brownish, a high percentage of MCC can be expected (in bloody
fluids we found up to 82 % maternal cells). False negative results are possible. We did not find clear morphological differences between maternal
and fetal interphase nuclei (except in same cases). Winsor et al.(1996)
found a rate of maternal cell contamination (MCC) in uncultured amniotic fluids, which is much higher than expected with cultured fluid. They
identified MCC in 1071500 (21.4%) uncultured interphase nuclei using X
and Y FISH probes, compared with 11500 (0.2%) in metaphases after cell
culture. Winsor mentioned that it is not always possible to differentiate
between maternal and fetal cells based on nuclear morphology. Although
they found it likely that most of the multi-lobulated nuclei are segmented
neutrophils from maternal blood, lobulated nuclei may also be fetal.
Specimens containing blood should therefore be excluded from analysis or the result should only be given if there are signals with a male
constellation.
Acknowledgements. Thanks are extended to Dr. Anita Rauch and Dr. Udo Trautmann for
helpful advice, to Michaela Kirsch and Anja Kollert for their advice and technical assistance
and Dr. Thomas Liehr for critically reading the manuscript.
References
BryndorfT, Christensen B, Vad M, Pamer J, Brocks V, Philip J (1997) Prenatal detection of chromosome aneuploidies by fluorescence in situ hybridization: experience
with 2000 uncultured amniotic fluid samples in a prospective preclinical trial. Prenat
Diagn 17:4,333-341
Claussen U, Ulmer R, Beinder E, Voigt H-J (1994) Six years experience with rapid karyotyping in prenatal diagnosis: correlations between phenotype detected by ultrasound and fetal karyotype. Prenat Diagn 14:113-121