DIII Type 7 is likely the original serologically defined DIIIb

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.