HNA-1a, HNA-1, and HNA-1c (NA1, NA2, SH) frequencies in African and American Blacks and in Chinese

The granulocyte antigens HNA-1a, -1b, and -1b (formerly named NA1, NA2 and SH) which reside on the neutrophil Fc gamma Receptor IIIb (Fc gamma RIIIb) play a major role in immune neutropenias and pulmonary transfusion reaction s. In an attempt to shed some light on the origin and history of these anti gens we typed the DNA of Blacks from South Africa (n=99), and Ghana (n=27), of 56 African Americans, and of 138 Chinese from Taiwan for HNA-1a,-1b, an d -1c antigens using polymerase chain reaction with sequence-specific prime rs (PCR-SSP). In African and American Blacks, the HNA-1b antigen was more f requent than HNA-1a (17 vs. 67% and 77 vs. 59%, respectively). In contrast, in Chinese HNA-1a was more frequent than HNA-1b (91 vs. 54%). We observed 3 individuals with Fc gamma RIIIB deficiency among the 126 tested African B lacks indicating a higher frequency of Fc gamma RIIIB deficiency in Blacks than the reported 0.1% in Europeans. In addition, the frequency of HNA-1c i n African and American Blacks (38 and 23%, respectively) was higher than th e reported 5% in Europeans. Among the 57 HNA-1c (+) Blacks, all were HNA-1b (+) but only 26 were HNA-1a (+) supporting the idea that the HNA-1c antige n is the result of an additional point mutation in the allele coding for HN A-1b. Recently, HNA-1a, -1b, and -1c (+) Europeans have been reported to ha ve three distinct Fc gamma RIIIB genes. Among 26 Blacks who had been typed HNA-1a,b,c (+) by PCR-SSP we identified only 7 having three Fc gamma RIIIB genes by DNA sequencing. When we sequenced the DNA of 6 HNA-1a,b,c (+) Euro peans we found 4 of the individuals had three Fc gamma RIIIB genes. Therefo re, we assume that in Africa the point mutation occurred first in the HNA-1 b allele resulting in the HNA-1c allele and the Fc gamma RIIIB gene duplica tion took place later.