Genetic predisposition for DPB susceptibility has been localized to two HLA haplotypes (a nucleotide or gene sequence difference between paired chromosomes, that is more likely to occur among a common ethnicity or trait) common to people of East Asian descent. HLA-B54 is associated with DPB in the Japanese, while HLA-A11 is associated with the disease in Koreans.[9] Several genes within this region of class I HLA are believed to be responsible for DPB, by allowing increased susceptibility to the disease.[7][10] The common genetic background and similarities in the HLA profile of affected Japanese and Korean individuals were considered in the search for a DPB gene.[10] It was suggested that a mutation of a suspected disease-susceptibility gene located somewhere between HLA-B[11] and HLA-A[12] had occurred on an ancestral chromosome carrying both HLA-B54 and HLA-A11. Further, it is possible that a number of genetic recombination events around the disease locus (location on a chromosome) could have resulted in the disease being associated with HLA-B54 in the Japanese and HLA-A11 in Koreans.