Linkage disequilibria between Duffy blood groups, Fc gamma IIa and Fc gamma IIIb allotypes.

Fc gamma receptors (Fc gamma R) on white blood cells and the Duffy blood group antigens on red blood cells are coded for on the long arm of chromosome 1. They appear in different allotypic forms: the high responder/low responder (HR/LR) forms of Fc gamma RIIa, the alloantigens NA1 and NA2 of Fc gamma RIIIb and the Duffy blood group antigens Fya and Fyb. The aim of this study was to analyze possible linkage disequilibria between these allotypic immunomodulatory receptors, and thus provide evidence for the existence of a hypothetical gene complex. The Duffy phenotype was determined by the indirect antiglobulin test, NA1/NA2 phenotypes by the granulocyte agglutination test and the HR/LR polymorphism by an immunophagocytosis assay. Two haplotypes were found to be in linkage disequilibrium. For the haplotype NA2, Fyb we calculated a delta-value of -0.07 and for the haplotype NA1, HR we obtained a delta-value of -0.02.