MOLECULAR ANALYSIS OF HLA CLASS-II POLYMORPHISM IN CROATIANS

HLA-class II polymorphisms have been studied in a population of 141 un related healthy Croatians using PCR amplification, followed by non-rad ioactive oligonucleotide hybridization. Thirty one DRB1, 8 DQA1, 13 DQ B1 and 16 DPB1 alleles were found in the tested population. DRB11601, 0701, 1501, 0101 and 1104 are the most frequent alleles at the DRB1 l ocus. At the DQA1 locus two alleles predominate: DQA1 0501 and 0102, while the most frequent DQB1 allele is 0301. Analysis of HLA-DPB1 pol ymorphism showed that, as in other Europeans, DPB1 0401 is the most f requent allele. Four different two locus haplotypic associations (DRB1 -DRB3, DRB1-DRB5, DRB1-DQB1 and DQA1-DQB1) as well as three locus DRB1 -DQA1-DQB1 haplotypic associations were assigned on the basis of known linkage disequilibria. Several unusual two-locus associations have be en observed: DRB10301-DRB3* 0202, DRB1*1501-DRB5*O2, DRB1*1601-DRB5*0 101, DRB11502-DRB5*0101, DQA1*0103-DQB1*0503 and DQA1*0501-DQB1 *0302 . Among 236 examined DRB1-DQA1-DQB1 haplotypic combinations, the most frequent was DRB11601-DQA1*0102-DQB1*0502 that was found with statist ically significant higher frequency than in other Europeans. Twenty-ei ght distinct probable haplotypes were observed just once, suggesting t hat the main characteristic of Croatian population is great heterogene ity of haplotypes. This study will serve as a reference for further an thropology studies, HLA and disease associations studies and for donor /recipient matching in organ and bone marrow transplantation.