Combining serology and molecular typing of weak D role in improving D typing strategy in Egypt.
BACKGROUND
Rh discrepancies are a problem during routine testing because of partial and weak D phenotypes. Some blood units with weak and partial D expression may escape detection by serology. Limitations of serology can be overcome by molecular typing. The objective of study was to compare currently used serologic methods with molecular analysis to determine the potential application of molecular methods to improve D typing strategies and to estimate the frequency of weak D types among the Arab population.


METHODS
Fifty blood donor and patient samples with discrepant results of D phenotyping were subjected to routine serology to define the D phenotype including monoclonal anti-D immunoglobulin M and indirect antiglobulin test. Commercially available panels of monoclonal anti-D were used for identification of partial D and weak D phenotypes. Genomic DNA was evaluated using allele-specific amplification polymerase chain reaction with sequence-specific primers to define weak D type.


RESULTS
Molecular typing confirmed most of the serology results; three samples that were not clear-cut serologically were identified by molecular typing, two samples as weak D Type 4.2 (DAR), and one sample as weak D Type 4.0. Another two samples identified by serologic panel as weak D were unresolved by molecular typing. A sample with partial D Type II by serology revealed a Weak D Type 4.0 by molecular typing. Results interestingly showed the high frequency of weak D Type 4.2 (DAR) in Egypt.


CONCLUSIONS
RHD molecular typing can solve discrepancies during routine testing due to partial and weak D phenotypes for better transfusion outcome.
Clinical Pathology Department, Faculty of Medicine, Dewan Aam El Mohafza, Fayoum, Egypt.
Abeer Mohamed
AM
Abdelrazik
Shahira Morsy
SM
Elshafie
Ghada M
GM
Ezzat Ahmed
Hossam M
HM
Abdelaziz
D001782:Blood Donors / Q000706:statistics & numerical data; D001788:Blood Grouping and Crossmatching / Q000379:methods*; D004534:Egypt / Q000453:epidemiology; D005260:Female; D018628:Gene Dosage; D005787:Gene Frequency; D006579:Heterozygote; D006801:Humans; D007231:Infant, Newborn; D058889:Molecular Typing / Q000379:methods*; D011247:Pregnancy; D015203:Reproducibility of Results; D012204:Rh-Hr Blood-Group System / Q000097:blood / Q000235:genetics* / Q000276:immunology; D012698:Serologic Tests
D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen