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Keywords:

  • PCR-ASP;
  • RHD*weak D partial 4.0;
  • Tunisia

Summary

Background and Objectives

D is the most immunogenic blood group antigen. About 1% of whites carry an altered RHD allele leading to quantitative or qualitative changes in the antigen D expression. T201R and F223V encoded by 602C>G and 667T>G are specific amino acid substitutions of the weak D type 4 cluster of African origin, comprising the alleles RHD*09.01, RHD*09.02, RHD*09.03, RHD*09.04 and RHD*09.05. The purpose of this study was to estimate the presence of these RHD genotypes in the Tunisian population.

Materials and Methods

Ethylenediaminetetraacetate blood samples from 907 D+ and 93 D− blood donors were tested for markers 602G and 667G by allele-specific primer-polymerase chain reaction (PCR-ASP). Samples with positive reactions were re-evaluated by DNA sequencing for RHD and RHCE exons 1–10 and adjacent intronic sequences.

Results

Among 907 D+ samples, 19 individuals were identified to harbour the RHD*weak partial 4.0 allele. RHCE sequencing post-haplotype-specific extraction (HSE) revealed an altered RHCE*ce(48C, 105T, 733G, 744C, 1025T) in those samples. The linkage of the RHCE polymorphisms to one haplotype was proven by DNA sequencing post-HSE.

Conclusion

The RHD*weak partial 4.0 allele syn. RHD*09.03 was estimated to occur 1 in 47 among D+ Tunisians. There was no evidence for other RHD alleles included in the weak D type 4 cluster.