As a clinical consequence, 74 blood donor samples carrying weak D and DEL phenotypes with the potential of causing secondary immunizations in recipients were reclassified as D+. Those samples were reliably amplified by RHD Exon 7 PCR; therefore, its usage in the Upper Austrian population is recommended. The association of the weak D type 4.3 samples with a ce leads to the policy that all apparently D- donors should be tested with genotyping methods; otherwise, potentially immunogenic RHD alleles may be overseen.

The results document a GYPA-B-A hybrid gene, probably produced via a single unequal homologous recombination event. A segmental transfer of GYPB seems most likely accounting for the allelic dropout.

The RHD*weak 4.3 allele with markedly reduced antigen D expression was shown to be associated with an altered RHCE gene formation leading to the expression of C(X) and VS. Its frequency was estimated 1 in 854 among apparently D- Upper Austrian blood donors.

No abstract