The results of a population survey on blood group distribution in Somalia, East Africa, are presented. Over 1,000 subjects were tested for most blood groups included in the survey. The sampling covered the whole country and was well in accordance with the population density as estimated by the recorded birth places of the subjects. Altogether, 46 blood group antigens were tested, partly common antigens within 11 of the major blood group systems, but also infrequent and very frequent antigens, some not tested before in Africa, were included. The results were compared with the available data for other related peoples and for populations from the same geographical area. The standard genetic distances were also applied in the comparison. The results suggest that only a minor component in the genetic constitution of the Somali population can be ascribed to Caucasian admixture. They are markedly in contrast with some earlier findings. During the survey we observed a previously unknown Rh gene complex occurring with a polymorphic frequency in Somalis.

Four unrelated propositi with an unusual Cx-positive Rh phenotype were found during a population survey of 513 Somalis. The Rh phenotypes of the propositi and their available relatives showed that the gene that produces the Cx antigen differs from that found in whites in that it is inherited with an Rh gene complex that produces no C or D. Instead, this gene complex produced es, c, and probably V, although it appeared that no f (ce) antigen was made. These findings suggest that Cx cannot be considered a simple variant form of C but rather a distinct rare Rh antigen that may occur in association with different Rh gene complexes.