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Weak D in the Tunisian population
Mouna Ouchari1, Houda Romdhane1, Taher Chakroun1
1Regional Blood Transfusion Centre, Sousse, Tunisia.
Blood Transfusion = Trasfusione Del Sangue
|November 5, 2014
Summary
Weak D type 4.0 is the most common weak D allele in Tunisia. Further sequencing is crucial to identify subtypes like weak D type 4.2, which is clinically significant for preventing anti-D alloimmunization.
Area of Science:
- Immunogenetics
- Blood Group Serology
- Molecular Diagnostics
Background:
- Over 90 weak D types are known globally.
- No prior data existed on weak D allele frequencies in the Tunisian population.
Purpose of the Study:
- To determine the prevalence and composition of weak D alleles in the Tunisian population.
- To identify specific weak D subtypes and their frequencies.
Main Methods:
- Polymerase chain reaction with sequence-specific primers (PCR-SSP) was used to test 1777 D+ and 223 D- blood donors.
- Specific markers (809G, 1154C, 8G, 602G, 667G, 446A, 885T) were analyzed.
- DNA sequencing of RHD exons 1-10 was performed for confirmation.
Main Results:
- Weak D type 4 was the most frequent weak D allele (1.2%) in D+ donors.
- Weak D type 4.0 was identified in all tested samples requiring sequencing.
- One D- sample exhibited weak D type 4.0 with a C+c+E-e+ phenotype, missed by serology.
Conclusions:
- Weak D type 4.0 is the predominant weak D allele in Tunisia.
- Full RHD sequencing is essential for accurate weak D subtyping, particularly for clinically significant types like 4.2.
- The study highlights the need for enhanced quality control in serological testing to detect all weak D variants.
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