engleski

HAPLOTYPIC ASSOCIATIONS OF TWO MOST COMMON HLA-B*27 ALLELES IN THE CROATIAN POPULATION

The HLA-B27 specificity is one of the most extensively studied HLA polymorphisms because of its remarkably strong association with ankylosing spondylitis (AS). The serologically well-defined HLA-B27 specificity is not a single allele but a family of at least 35 different alleles, named HLA-B*2701 to HLA-B*2736. The frequencies vary depending on the race, with B*2705 as the most common subtype. The purpose of the present study was to analyze haplotypic associations of two most common HLA-B*27 subtypes (B*2702 and B*2705) in the Croatian population. One hundred and eleven unrelated HLA-B*27 positive individuals were included, none of them had any sign of AS. The total number of analyzed haplotypic associations was 112 because one individual was homozygous for HLA-B*27. HLA-B*27 alleles as well as HLA-A and DRB1 specificities were tested by PCR-SSP method. Among seven different B*27 alleles observed among our individuals, B*2705 was the most frequent (61.6%), followed by B*2702 (30.4%), while the frequency of all other observed alleles (B*2701, B*2703, B*2704, B*2708 i B*2714) was less than 2.0%. HLA-A*02 was the most frequent specificity at HLA-A locus in both groups of haplotypic associations (B*2702 and B*2705) and no difference in distribution of HLA-A genes was observed between two groups. Analysis of HLA-B*2702 haplotypic associations showed the high frequency of DRB1*16 (41.2%) in comparison to B*2705 haplotypic associations (4.0%) with significant P value (P<0.00001). HLA-DRB1*01 demonstrated significantly higher presence among sixty-nine B*2705 haplotypic associations compared to B*2702 haplotypic associations (28.0% vs. 1.5% ; P<0.00001). In conclusion, our data imply that the presence of DRB1*16 specificity among B*27 positive individuals can suggest the presence of B*2702 subtype.

HLA-B*27; CROATIAN POPULATION

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