Molecular diversity of HLA-DR4 haplotypes (major histocompatibility complex/cDNA dones/DR and DQ/gene conversion)

Complementary DNA (cDNA) clones encod- ing g3 chains of the DR and DQ regions and a chains of the DQ region were isolated and sequenced from four homozygous DR4 cell lines of different HLA-D types: GM3103(Dw4), FS(Dw1O), BIN40(Dw14), and KT3(Dwl5). When compared with each other and with a previously published sequence from a DR4 (Dw13 cell line), the variability of DR61 gene products is generally restricted to the region around amino acid position 70, with an additional polymorphism at position 86. Many of these differences, including an unusual amino acid substitution at position 57 in the Japanese cell line KT3(Dwl5), may be due to gene conversion events from the DR62 or DXB genes. In