Fetal blood group genotyping: present and future

Area of Science:

• Genetics
• Immunology
• Obstetrics

Background:

• Hemolytic disease of the fetus and newborn (HDFN) is a risk when mothers have antibodies to RhD.
• Fetal DNA analysis in maternal plasma offers a non-invasive method for blood group determination.

Purpose of the Study:

• To evaluate the accuracy of fetal RhD blood group prediction from maternal plasma DNA.
• To assess the utility of fetal blood group typing for managing RhD-negative pregnancies.

Main Methods:

• Real-time quantitative polymerase chain reaction (RQ-PCR) was used to detect RHD exons.
• Internal controls including SRY and biallelic polymorphisms were incorporated.
• Fetal typing for K, Rhc, and RhE using single nucleotide polymorphisms (SNPs) was also performed.

Main Results:

• Over 533 pregnancies tested since 2000, 327 with known infant RhD showed one false-positive and one false-negative result.
• Introduction of fetal typing for K, Rhc, and RhE in 2004.
• Trials for automated fetal RhD typing from maternal plasma are underway.

Conclusions:

• Non-invasive fetal RhD testing from maternal plasma is a reliable method.
• Automated testing aims to identify RhD-negative fetuses in RhD-negative women to avoid unnecessary RhD immunoglobulin prophylaxis.
• This technology has the potential to optimize antenatal care and reduce healthcare costs.