Limited Genetic Diversity in the HLS Class II DP Region of the Atayal Tribe, with Dominant Alleles DPA1*02022 and DPB1*0501 by High Resolution Sequencing Based TypingLimited Genetic Diversity in the H

The polygenic HLA (human leukocyte antigen) gene complex is the most polymorphic cluster of functional human genes known. The degree of HLA polymorphism in an ethnic group determines the size of a donor registry for finding an HLA-matched unrelated donor for solid organ or bone marrow transplantation. In this report, we use sequencing based typing (SBT) to analyze the degree of polymorphism of the class II HLA-DP genes from Atayal tribe members living in the Hualien county (Taiwan) at 121∘ East and 24∘North. DNA was isolated from peripheral blood cells from 60 Atayal individuals. HLA-DPA1 and DPB1 alleles were identified by sequencing the polymorphic second exon. Three alleles were found for the DPA1 locus, among which 02022 had the highest allele frequency (59%), followed by 0103 (17%) and 02011 (9%). Five alleles were found for the DPB1 locus, with 0501 having the highest allele frequency (75%), followed by 0301 (9%), 1401 (7%), 02012 (6%) and 1301 (2%). Five two-locus haplotypes were inferred by a maximum-likelihood method: DPA1*02022-DPB1*0501 (57.7%), dpa1*0103-DPB1*0301 (9.2%), DPA1*02011-DPB1*1407 (7.5%), DPA1*0103-DPB1*02012 (5.8%) and DPA1*02011-DPB1*1301 (1.7%). These results suggest that there is linkage disequilibrium within the HLA-DP region in the Atayal tribe. Remarkable is the high frequency (55%) of individuals potentially homozygous for both DPA1*02022 and DPB1*0501 alleles. The Atayal tribe seems to show a very limited HLA-DP polymorphism.