Background: Due to their homology, close proximity, and opposite orientation, RHD and RHCE can exchange nucleotides giving rise to variant alleles. Some of these variants encode the so-called partial phenotypes. The DIII partial D category has been subdivided into DIIIa, DIIIb, DIIIc, DIII Type 4, DIII Type 6, and DIII Type 7. During DNA-based screening tests, we identified a second example of DIII Type 7 in a Dce donor from South Africa. Our study describes hemagglutination tests on this sample and raises a question regarding the molecular basis of the originally defined DIIIb category.
Study design and methods: Hemagglutination and DNA testing were performed by standard techniques.
Results: Red blood cells from this DIII Type 7 donor typed D+C-E-c+e+G-, DAK+ and did not react with anti-D made by people with the DIII phenotype. The allele is RHD*DIII 150C, 178C, 201A, 203A, 307C, 410T, 455C, 602G, 667G.
Conclusions: Based on the serotype and ethnicity (black African), it is likely that DIII Type 7 is the originally defined DIIIb category.
© 2011 American Association of Blood Banks.