Red blood cell genotyping in China

The risk to future pregnancies of transfusing Rh(D)-negative females of childbearing potential with Rh(D)-positive red blood cells during trauma resuscitation is dependent on their age at transfusion

BACKGROUND

A risk assessment model for predicting the risk of haemolytic disease of the fetus and newborn (HDFN) in future pregnancies following the transfusion of Rh(D)-positive red blood cell (RBC)-containing products to females of childbearing potential (FCP) was developed, accounting for the age that the FCP is transfused in various countries.

METHODS

The HDFN risk prediction model included the following inputs: risk of FCP death in trauma, Rh(D) alloimmunization rate following Rh(D)-positive RBC transfusion, expected number of live births following resuscitation, probability of carrying an Rh(D)-positive fetus, the probability of HDFN in an Rh(D)-positive fetus carried by an alloimmunized mother. The model was implemented in Microsoft R Open, and one million FCPs of each age between 18 and 49 years old were simulated. Published data from eight countries, including the United States, were utilized to generate country-specific HDFN risk estimates.

RESULTS

The risk predictions showed similar characteristics for each country in that the overall risk of having a pregnancy affected by HDFN was higher if the FCP was younger when she received her Rh(D)-positive transfusion than if she was older. In the United States, the overall risk of HDFN if the FCP was transfused at age 18 was 3·4% (mild: 1·20%, moderate: 0·45%; severe: 1·15%; IUFD: 0·57%); the risk was approximately 0% if the FCP was 43 years or older at the time of transfusion.

CONCLUSION

This model can be used to predict HDFN outcomes when establishing transfusion policies as it relates to the administration of Rh(D)-positive products for massively bleeding FCPs.

[Genotyping of RhD-negative blood samples diagnosed by serological tests from patients waiting for kidney transplantation]

OBJECTIVE

To compare the accuracy of serological and molecular approaches to identification of RhD-negative patients waiting for kidney transplantation.

METHODS

A total of 103 RhD-negative blood samples by serological test were collected from patients waiting for kidney transplantation between January, 2006 and January, 2016. Quantitative PCR and sequencing were used to verify the results of RHD genotyping, and the false negative rates of the serological and molecular methods for RhD genotyping were compared.

RESULTS

Among the 103 blood samples, true RhD negativity (with all the 10 exons missing) was found in 56 samples (54.5%), and false RhD negativity (RhD positivity with loss, repetition, or missense mutation in the 10 exons) in 47 samples (45.6%). In the 47 false RhD-negative cases, weak D was detected in 1 case (2.1%), partial D in 13 cases (27.7%), and D-elution in 33 cases (70.2%). The detection rates of RhD negativity differed significantly between the serological and molecular methods (P<0.05).

CONCLUSION

Serological test is associated with a high false negative rate in detecting RhD blood group, and the use of the molecular approach has important clinical significance in accurate RhD genotyping for patients waiting for renal transplantation.