Partial D, weak D types, and novel RHD alleles among 33,864 multiethnic patients: implications for anti-D alloimmunization and prevention.
BACKGROUND
The D antigen includes category D, partial D, and weak D types, which are important because anti-D alloimmunization can occur in some but not all persons that express a variant RHD allele. At present, there is little prospective information on the prevalence of D variants among obstetric patients and potential transfusion recipients.


METHODS
The RHD alleles were prospectively examined in a large patient population identified on the basis of a difference in anti-D reactivity between two reagents.


RESULTS
Fifty-five discrepancies (0.96% of D-) were noted among 33,864 ethnically diverse patients over 18 months, of which 54 represented mutated RHD alleles. Seven obstetric patients were assigned D- status based on serology; only 1 patient had a partial RHD allele. Ten of 25 (36%) obstetric patients and 4 of 6 (67%) female potential transfusion recipients of childbearing age or younger were assigned D+ status, and they expressed a D variant known to permit anti-D alloimmunization. In total 20 RHD alleles were identified including category, DVa or DVa-like alleles (n = 7), DAR (n = 8), and four novel RHD alleles including two new DAU alleles.


CONCLUSIONS
Given the complexity of D antigen expression, it is concluded that some clinically important D variants identified by standard serologic analysis phenotype as D+ and are potentially at risk for the development of anti-D.
Denomme
Gregory A
GA
Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada. greg.denomme@bloodservices.ca
Wagner
Franz F
FF
Fernandes
Bernard J
BJ
Li
Wei
W
Flegel
Willy A
WA
D000328:Adult; D000483:Alleles; D019943:Amino Acid Substitution; D001771:Blood Banks / Q000592:standards; D001787:Blood Group Incompatibility / Q000453:epidemiology / Q000209:etiology* / Q000276:immunology / Q000517:prevention & control; D001788:Blood Grouping and Crossmatching / Q000592:standards; D001803:Blood Transfusion / Q000592:standards; D004252:DNA Mutational Analysis; D004899:Erythroblastosis, Fetal / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D005006:Ethnicity / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D007112:Immunity, Maternally-Acquired; D007231:Infant, Newborn; D007518:Isoantibodies / Q000096:biosynthesis / Q000276:immunology*; D008297:Male; D009864:Ontario / Q000453:epidemiology; D010641:Phenotype; D017354:Point Mutation; D011247:Pregnancy; D011295:Prenatal Care / Q000592:standards; D012203:Rh Isoimmunization / Q000453:epidemiology / Q000209:etiology* / Q000276:immunology / Q000517:prevention & control; D012204:Rh-Hr Blood-Group System / Q000145:classification / Q000235:genetics* / Q000276:immunology; D018029:Rho(D) Immune Globulin; D012306:Risk; D009626:Terminology as Topic; D065227:Transfusion Reaction
D007518:Isoantibodies; C061961:RHO(D) antibody; D012204:Rh-Hr Blood-Group System; D018029:Rho(D) Immune Globulin; C026410:Rho(D) antigen