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Updated: Feb 8, 2026
Determining the Role of Maternally-Expressed Genes in Early Development with Maternal Crispants
Published on: December 21, 2021
Interfering effect of maternal cell contamination on invasive prenatal molecular genetic testing
Katalin Koczok1, Éva Gombos1, László Madar1
1Division of Clinical Genetics, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
Objective:
Fetal samples obtained by invasive techniques are prone to maternal cell contamination (MCC), which may lead to false genotyping results. Our aim was to determine 3 molecular genetic tests' sensitivity to MCC.
Method:
By mixing experiments, 1%, 5%, 10%, 20%, 30%, and 40% MCC was simulated, and significant MCC levels were determined for Sanger DNA sequencing, multiplex ligation-dependent probe amplification (MLPA), and pyrosequencing, a next-generation sequencing method.
Results:
For Sanger sequencing, the limit of sensitivity to MCC was 5% to 30%. For MLPA, a higher proportion of MCC (≥40%) was shown to lead to diagnostic uncertainty. In contrast, pyrosequencing proved to be very sensitive to MCC, detecting a proportion as low as 1%.
Conclusion:
In the case of Sanger sequencing, sensitivity to MCC was variable, while for MLPA, only high levels of MCC proved to be significant. Although the next-generation sequencing method was sensitive to low-level MCC, if MCC level is determined in parallel, accurate quantification of allelic ratios can help to interpret the diagnostic results. Knowledge of significant MCC levels allows correct prenatal diagnosis even if samples are not purely of fetal origin and repeated sampling can be avoided in many of the cases.
Insights
Maternal cell contamination (MCC) can affect fetal genetic testing. Pyrosequencing is highly sensitive to low-level MCC, while Sanger sequencing and MLPA have higher detection limits, aiding accurate prenatal diagnosis.
Area of Science:
- Molecular Genetics
- Prenatal Diagnostics
Background:
- Fetal samples from invasive procedures risk maternal cell contamination (MCC).
- MCC can compromise the accuracy of fetal genotyping and prenatal diagnosis.
Purpose of the Study:
- To evaluate the sensitivity of three molecular genetic tests to MCC.
- To determine the impact of varying MCC levels on diagnostic accuracy.
Main Methods:
- Simulated varying percentages of MCC (1-40%) in fetal samples.
- Assessed sensitivity to MCC for Sanger DNA sequencing, multiplex ligation-dependent probe amplification (MLPA), and pyrosequencing.
Main Results:
- Sanger sequencing showed sensitivity to MCC between 5% and 30%.
- MLPA indicated diagnostic uncertainty at MCC levels of 40% or higher.
- Pyrosequencing demonstrated high sensitivity, detecting MCC as low as 1%.
Conclusions:
- Pyrosequencing is highly sensitive to low-level MCC, unlike Sanger sequencing and MLPA.
- Determining MCC levels alongside genetic testing aids accurate interpretation and avoids repeat sampling.
- Knowledge of MCC thresholds supports reliable prenatal diagnosis even with non-pure fetal samples.
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