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Updated: Aug 27, 2025
FISH for Pre-implantation Genetic Diagnosis
Published on: February 23, 2011
Non-Invasive Fetal K Status Prediction: 7 Years of Experience
Klaus Rieneck1, Frederik Banch Clausen1, Thomas Bergholt2
1Department of Clinical Immunology, Rigshospitalet, Copenhagen, Denmark.
Insights
Predicting fetal K status non-invasively using maternal plasma DNA is now possible with a new NGS method. This allows early intervention for pregnancies at risk of hemolytic disease due to maternal anti-K antibodies.
Area of Science:
- Immunogenetics
- Maternal-Fetal Medicine
- Genomic Medicine
Background:
- The Kell blood group system's K and k antigens are critical in transfusion medicine.
- Maternal anti-K IgG antibodies pose a significant risk to K-positive fetuses, potentially causing fetal demise.
- Accurate prenatal K status prediction is essential for managing pregnancy risks and enabling timely intervention.
Purpose of the Study:
- To develop and validate a non-invasive method for predicting fetal K blood group status using maternal plasma DNA.
- To establish a reliable assay for early pregnancy risk assessment in cases of maternal anti-K immunization.
- To provide a basis for effective pregnancy management and intervention strategies.
Main Methods:
- Maternal plasma DNA was analyzed from 43 women immunized against K, with samples collected from 10 to 38 weeks of gestation.
- Polymerase Chain Reaction (PCR) amplified the KEL*01.01/KEL*02 single nucleotide variant without allele specificity.
- Next-Generation Sequencing (NGS) determined the ratio of KEL*01.01 and KEL*02 reads for fetal K status prediction.
Main Results:
- The developed NGS-based assay accurately predicted fetal K status in all cases where postnatal serological data was available (n=34).
- Predictions were consistent with newborn serology, demonstrating the method's reliability.
- The assay was effective even with samples obtained as early as 10 weeks of gestation.
Conclusions:
- An NGS-based method for non-invasive fetal K status prediction has been successfully developed.
- The assay requires careful optimization of primer design, sample handling, and analytical procedures.
- This method enables early detection and timely clinical intervention for pregnancies at risk of hemolytic disease of the fetus and newborn (HDFN).
Introduction:
In the Kell blood group system, the K and k antigens are the clinically most important ones. Maternal anti-K IgG antibodies can lead to the demise of a K-positive fetus in early pregnancy. Intervention can save the fetus. Prenatal K status prediction of the fetus in early pregnancy is desirable and gives a good basis for pregnancy risk management. We present the results from 7 years of clinical experience in predicting fetal K status as well as some theoretical considerations relevant for design of the assay and evaluation of results.
Methods:
Blood was collected from 43 women, all immunized against K, at a mean gestational age of 18 weeks (range 10-38). A total of 56 consecutive samples were tested. The KEL *01.01 /KEL *02 single nucleotide variant that determines K status was amplified from maternal plasma DNA by PCR without allele specificity. The PCR product was sequenced by NGS technology, and the number of sequenced KEL *01.01 and KEL *02 reads were counted. Prediction of the fetal K status was based on this count and was compared with the serologically determined K status of the newborns.
Results:
All fetal K predictions were in accordance with postnatal serology where available (n = 34), using our current data analysis.
Conclusion:
We have developed an NGS-based method for the non-invasive prediction of fetal K status. This approach requires special considerations in terms of primer design, stringent preanalytical sample handling, and careful analytical procedures. We analyzed samples starting at GA 10 weeks and demonstrated the correct prediction of fetal K status. This assay enables timely clinical intervention in pregnancies at risk of hemolytic disease of the fetus and newborn caused by maternal anti-K IgG antibodies.
