RHD*weak partial 4.0 is associated with an altered RHCE*ce(48C, 105T, 733G, 744C, 1025T) allele in the Tunisian
M Ouchari1, H Polin, H Romdhane
1Unité de recherche "UR06SP05" Centre Régional de Transfusion Sanguine, Sousse, Tunisia.
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.
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