Six years' experience performing RHD genotyping to confirm D- red blood cell units in Germany for preventing anti-D immunizations.
BACKGROUND
Red blood cell (RBC) units of D+ donors are falsely labeled D- if regular serologic typing fails to detect low D antigen expression or chimerism. The limitations of serology can be overcome by molecular typing.


METHODS
In January 2002, we introduced a polymerase chain reaction (PCR)-based assay for RHD as a routine test for first-time donors who typed D- by serologic methods including the indirect antiglobulin test. Samples were tested in pools of 20 for the RHD-specific polymorphism in Intron 4. RHD alleles were identified by PCR and nucleotide sequencing.


RESULTS
Within 6 years, 46,133 serologically D- first-time donors were screened for the RHD gene. The prevalence of RHD gene carriers detected by this method was 0.21 percent. Twenty-three RHD alleles were found of which 15 were new. Approximately one-half of the RHD gene carriers harbored alleles expressing a DEL phenotype resulting in a prevalence of 0.1 percent.


CONCLUSIONS
The integration of RHD genotyping into the routine screening program was practical. We report 6 years' experience of this donor testing policy, which is not performed in most transfusion services worldwide. RBC units of donors with DEL phenotype have been reported to anti-D immunize D- recipients. We transferred those donors to the D+ donor pool with the rationale of preventing anti-D immunizations, especially dreaded in pregnancies. For each population, it will be necessary to adapt the RHD genotyping strategy to the spectrum of prevalent alleles.
Flegel
Willy A
WA
German Red Cross (DRK) Blood Donor Service Baden-Württemberg-Hessen, Institute of Clinical Transfusion Medicine and Immunogenetics Ulm, Ulm, Germany. willy.flegel@uni-ulm.de
von Zabern
Inge
I
Wagner
Franz F
FF
D000483:Alleles; D001483:Base Sequence; D001782:Blood Donors; D003062:Codon; D018076:DNA, Complementary / Q000235:genetics; D004912:Erythrocytes / Q000276:immunology* / Q000378:metabolism*; D005091:Exons / Q000235:genetics; D005838:Genotype; D005858:Germany; D006801:Humans; D007114:Immunization; D007518:Isoantibodies / Q000276:immunology*; D010641:Phenotype; D012204:Rh-Hr Blood-Group System / Q000235:genetics* / Q000276:immunology*; D018029:Rho(D) Immune Globulin; D013997:Time Factors
D003062:Codon; D018076:DNA, Complementary; D007518:Isoantibodies; C061961:RHO(D) antibody; D012204:Rh-Hr Blood-Group System; D018029:Rho(D) Immune Globulin; C026410:Rho(D) antigen