HLA-DR,DQ NUCLEOTIDE-SEQUENCE POLYMORPHISMS IN 5 MELANESIAN POPULATIONS

HLA-DRB1 nucleotide sequence polymorphisms have been examined in 304 Melanesians from the Papua New Guinean coast (Madang), islands (Rabaul) and highlands (Goroka), and from New Caledonia and Fiji. A total of 20 HLA-DRB1 alleles were detected by oligonucleotide hybridizations of exon 2 HLA-DRB1 polymerase chain reaction products, in a typing protocol designed to detect all 42 officially-designated HLA-DRB1 alleles. DRB1*1502 and 1101 alleles were the most common alleles in coastal and island Melanesians, while DRB1*1501, 1502 and 1408 predominated in Papua New Guinean highlanders. Undefined mixed lymphocyte reaction determinants in earlier studies of Melanesians could be accounted for in the present study as DRB1*0410, 1407 and 1408 in Papua New Guinean highlanders and as DRB1*1104 and 1602 in coastal people. Nucleotide sequence polymorphisms at HLA-DQA1, -DQB1, -DRB3 and -DRB5 were also determined for estimating HLA-DR,DQ allelic disequilibrium relationships; unusual haplotypes in Melanesians included DBR1*1502, DRB5*0101 and DRB1*0410, DQB1*0402. Previous claims of limited heterogeneity in the HLA-DR allele repertoire in Melanesians are now seen to reflect limitations of early typing reagents rather than any dramatic restriction in HLA-DR allelic diversity.