A DV‐like phenotype is obliteratedby A226P in the partial D DBS

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Abstract
BACKGROUND:In D category V types, theRHDexon 5 or parts thereof are replaced by the correspondingRHCEDNA segments. In D category V types I and II, the amino acid at position 226 is alanine, which is typical of the prevalentRHDallele and is observed in allRHCEalleles encoding the antigen e. A proline at position 226 inRHCEencodes the antigen E.STUDY DESIGN AND METHODS:A blood sample of ccDEe phenotype was referred as suspected D category VI. TheRHDnucleotide sequence and the D epitope pattern were determined.RESULTS:A new partial D, DBS, encoded by anRHD‐RHcE(5)‐RHDhybrid allele, was found. Although it differed from DVatype II by an A226P substitution only, it lacked epitopes epD4, epD12, epD17, epD18, and epD22 that were present in DVa. The 5′ breakpoint region was located between the deletion inRHDintron 4 and the first polymorphic nucleotide of DBS exon 5.CONCLUSION:The phenotypes ofRHDalleles with gene conversions limited to exon 5 depended critically on the amino acid at position 226. If alanine was present at this position, gene conversions involving E233Q led to a DVa‐like phenotype. If proline was present, many additional epitopes were lost, and the phenotype became reminiscent of DFR. The 5′ breakpoint region is shared by 10 alleles and may represent the most active “hot spot” for gene conversions known inRH.