FcγRIIIB polymorphism:: evidence that NA1/NA2 and SH are located in two closely linked loci and that the SH allele is linked to the NA1 allele in the Danish population

BACKGROUND: The neutrophil-specific antigens NA1, NA2, and SH are well-recognized allotypic forms of Fc gamma RIIIB. Individuals carrying all three Fc gamma RIIIB genes were recently described. STUDY DESIGN AND METHODS: A Danish population (n = 200) was typed for NAI, NA2, and SH by polymerase chain reaction with sequence-specific primers (PCR-SSP). Twelve individuals with three Fc gamma RIIIB genes were further genotyped by PCR-based restriction fragment length polymorphism and by DNA sequencing. Family studies were performed on three individuals who carry three Fc gamma RIIIB genes. RESULTS: The gene frequencies for NAI, NA2, and SH were 0.365, 0.635, and 0.030, respectively. In eight individuals (4%), all three Fc gamma RIIIB genes were identified. All 12 SH+ individuals were NA1+. CONCLUSION: The NAI, NA2, and SH gene frequencies observed in Danes are similar to those in other white populations. The distribution of Fc gamma RIIIB genotypes in the Danish population strongly indicates that the NA and the SH systems are located in two closely linked loci and that SH is closely linked to NA1. Finally, a new PCR-SSP was developed to distinguish NA2 from SH.