Distinct distribution of killer-cell immunoglobulin-like receptor genes in the Mugil and Ilaita areas of Papua New Guinea.

The frequency of the killer-cell immunoglobulin-like receptor (KIR) genes and transmembrane alleles of KIR2DL4 were studied in coastal (Mugil community) and inland (Ilaita community) communities in Papua New Guinea. Linkage disequilibria between KIR genes and between alleles of KIR2DL4 and the KIR genes were similar to those found in other populations suggesting conservation of the usual gene order in Papua New Guinean haplotypes. Significant differences in the frequency of KIR genes were found between the two populations despite being separated by only 300 km. Examples of individuals who lacked the KIR2DL4 gene and others whose KIR2DL4 allele appeared to have 11 adenines in the polyadenine tract in exon 6 were identified. A relatively low frequency of the KIR A haplotype was found in both populations and particularly in the inland community. The KIR gene frequencies were consistent with the inland Ilaita community being closely related to Australian Aborigines and southern Indians, whereas the KIR gene frequencies of the coastal Mugil community appeared to have been influenced either by recent or ancient admixture from populations with a higher frequency of the KIR A haplotype.