Serological Characteristics of Partial D Antigen Category VI in 8 Unrelated Blood Donors

Abstract

Classification of subjects with a partial D antigen is traditionally performed with immune anti-D sera. The development of monoclonal antibodies enables a fine analysis to be made of the specificity of the epitopes that are present or missing in these cases. A systematic search in a Caucasian donor population of 17,500 revealed 8 unrelated male individuals (frequency 0.05%) with a red cell phenotype characteristic of partial D category VI, but without anti-D in their serum. The relation to the ‘classic’ partial D category VI was investigated and is discussed, as is the observed serological heterogeneity of the partial D category VI group. Clinical consequences for the prevention of immunization of these subjects are mentioned.

Frequencies of the Blood Groups ABO, Rhesus, D Category VI, Kell, and of Clinically Relevant High-Frequency Antigens in South-Western Germany

“…The frequency observed in England (0.04%) [14] is within our confidence limites and hence not significantly different. In contrast, D VI is about three times more frequent in the Dutch compared to the German population (p < 0.02, two-sided chisquare test) [11,15]. This significant variation of D VI phenotype frequencies underscores the notion that frequency data and the transfusion policies based thereon may not be substituted uncritically between different populations [16].…”

“…4 The observed frequencies of Rh-D-negative phenotypes with C and/or E in 624,163 donors were: Ccddee 0.83% (n = 5,156); ccddEe 0.43% (2,693); CcddEe 0.014% (88); CCddee 0.012% (75); ccddEE 0.0021% (13); CCddEe 0.00016% (1); CcddEE 0.00016% (1); CCddEE was not observed (0). [11,12].…”

Comprehensive analysis of RHD alleles in Argentineans with variant D phenotypes

“…This was also an unexpected result since the reported frequencies of D category VI for Europeans range from 1 in 2000 to 1 in 5000 and some authors have encountered up to 8% of DVI phenotypes among samples with serologically unclear D status. Indeed, DVI alleles have been described in the Spanish population, with a specific molecular background ( DVI Type 4 ) being prevalent in their DVI population 4,15,30‐32 . The admixture events that took place at the beginning of the 20th century mainly between Spanish and Italian immigrants with the local population probably diminished the frequency of this partial D variant in the Argentinean population.…”

Do we need to be more concerned about weak D antigens?

“…Only approximately 5 to 10 percent of the weak D are partial D; many partial D phenotypes present as normal D types (e.g., react strongly with routine anti‐D) so they are often not classified until they make anti‐D. Most D+ individuals making anti‐D are partial D category DVI (the frequency of DVI is 0.02‐0.05 percent of Caucasian persons) 37‐41 and typically present as weak D (DVI lack many of the D epitopes); other partial D who can make anti‐D (e.g., Vb and FPTT) may appear to have normal strength D antigens.…”