engleski

The Study on the Extended Haplotypes of Rare HLA-B*2730 Allele Using Microsatellite Loci

The aim of the present study was to compare haplotypes of the most frequent B*27 alleles among Croatians (B*2702 and *2705) and the rare B*2730 allele. For this purpose, 37 families with members carryinghuman leukocyte antigen (HLA)-B27were selected. All individuals were analysed for eight microsatellites (Msats): D6S2927, short tandem repeat – MHC class I-related gene (STR_MICA), D6S2793, D6S2811, tumor necrosis factor a (TNFa), tumor necrosis factor d (TNFd), D6S273 and D6S1014, while individuals carrying the HLA-B27 specificity were subtyped. Of 39 analysed haplotypes, 20 individuals had B*2702, 15 subjects were positive for the B*2705 allele, the B*2730 allele was found in three haplotypes from different families, while one individual carried theB*2703 allele.HLA-A3 and -DRB1*16were shared by all three B*2730 haplotypes. The DRB1*16 allele was also observed in themajority of B*2702 haplotypes (76.5%), while HLA-A3 was, after HLA-A2, the second most frequent HLA-A specificity in B*2702 haplotypes. No such correlation was found for the B*2705 haplotypes. Msat analysis showed that B*2730 haplotypes also share the same allele at all testedMsats. The D6S2927, D6S2793, MICA and TNFdMsats were not useful in distinguishing B*2702 and B*2705 alleles because D6S2927-213bp, STR_MICA-179bp, D6S2793-206bp, D6S2811-83bp and TNFd-130bp were detected in almost all cases. Conversely, for the TNFa, D6S273 and D6S1014 loci, haplotypes carryingB*2702 andB*2730 shared a singleMsat allele in themajority of cases (TNFa- 113bp, D6S1014-134bp and D6S273-134bp), which was not observed for B*2705 haplotypes. In conclusion, the similarity between B*2702 and B*2730DNAsequences as well as their sharing of the same haplotypic combinations corroborates the proposed mechanism of B*2730 evolution from B*2702 by interallelic recombination.

B*2730; B*27 subtypes; extended haplotypes; microsatellites; population studies

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