Phylogeny of
RHD in humans. A phylogenetic tree ofRHD is shown for most “African” alleles and representative “Eurasian” alleles. There are 4 main clusters that may be discerned. The DIVa cluster encompasses the DIVa,DIII type 4, and Ccdesalleles. Most samples harboring these alleles share 3 characteristic amino acids (62F, 137V, 152T) that are ancestral, because they are also observed in chimpanzee RH (Pan troglodytesRh-like protein IIR). The weak D type 4 cluster encompassesDAR, DOL, and RHDΨ, too. For this cluster, the RHD (F223V) allele is postulated36but has yet to be shown extant. DIII type 5, a newRHD allele resembling DIIIa, evolved by a recombination between alleles of the DIVa and the weak D type 4 clusters. For the DAU cluster, its primitive type DAU-0 has been found and was shown to be the most frequent DAU allele in Europeans. All enumerated alleles occurred in a cDehaplotype and were predominantly observed in Africans. In contrast, most other RHD alleles were typical for Eurasians, derived from standard Eurasian RHD by a single event, occurred in a CDe or cDE haplotype, and formed the Eurasian D cluster. The tree was mainly based onRHD allelic variability, and dismisses the largely unknownRHCE variability beyond the C and E polymorphism. For each evolutionary step, the event is indicated; the depicted distances of the alleles are arbitrary.
