HLA class I and class II polymorphism in the population of Rijeka, Croatia

Area of Science:

• Immunogenetics
• Population Genetics

Background:

• Human Leukocyte Antigen (HLA) genes are highly polymorphic and crucial for immune response.
• Understanding HLA antigen and haplotype frequencies is vital for population genetics and transplantation compatibility.

Purpose of the Study:

• To determine the frequencies of HLA-A, -B, and -DR antigens and haplotypes in the Rijeka population.
• To compare these frequencies with broader Croatian and European populations.
• To investigate associations between specific HLA antigens and haplotypes.

Main Methods:

• Analysis of HLA-A, -B, and -DR antigen and haplotype frequencies in 117 healthy blood donors from Rijeka.
• Statistical comparison of observed frequencies against reference data for Croatian and European populations.
• Linkage disequilibrium analysis to identify associations between HLA alleles.

Main Results:

• Identified high-frequency antigens: A2 (27.2%), A9 (16.3%), B5 (14.8%), B12 (11.8%), B18 (11.8%), DR5 (21.6%), and DR6 (13.8%).
• Observed statistically significant differences in 1 antigen compared to the general Croatian population and 8 antigens compared to European populations.
• Noted high-frequency haplotypes including HLA-A2, B5; HLA-A2, B12; HLA-A2, B18; HLA-B12, DR2; and HLA-B18, DR5.
• Found a strong association between HLA-B5 and HLA-DR5 (6.41%), consistent with other populations.

Conclusions:

• The Rijeka population exhibits significant diversity in HLA haplotypes.
• Observed genetic variations suggest a history of admixture with neighboring immigrating populations.
• Findings contribute to the understanding of regional HLA polymorphism in Europe.