The characteristics of allelic polymorphism in killer-immunoglobulin-like receptor framework genes in African Americans.

The frequencies of alleles of killer cell immunoglobulin-like receptor genes, KIR3DL3 and KIR3DL2, and the carrier frequency of KIR2DL4 alleles have been determined from a population of African Americans (n = 100) by DNA sequencing of the coding regions. Fifty alleles of KIR3DL3 were observed with the most frequent, KIR3DL3*00901 (13%). KIR3DL2 was also diverse; 32 alleles with KIR3DL2*00103 the most frequent (17%). For KIR2DL4, of the 18 alleles observed, one allele, KIR2DL4*00103, was found in 64 of the 100 individuals. Thirty-six novel alleles encoding a total of 28 unique receptors are described. Pairwise comparisons among all of the alleles at each locus suggest a predominance of synonymous substitutions. The variation at all three framework loci fits a neutral model of evolution.