Objectives: Coeliac disease (CD) has one of the strongest class II HLA association of any human disease. The goal of this study was to establish the frequency of HLA-DR and DQ antigens, as well as common HLA-DR-DQ haplotypes among CD patients. No similar study has previously been done in Croatian patients.
Patients and controls: There were 58 biopsy proven patients with CD. The control groups comprised 502 and 118 healthy person for HLA-DR and HLA-DQ typing, respectively.
Methods: The class II HLA-DR and DQ antigens typing were carried out by standard microcytotoxicity assay for B cells. Only antisera to three specificities (DQ1, 2 and 3) were available to us at the time of the study.
Results: We confirmed the high frequency of HLA-DR3 (84.48%; RR = 23.7; p < 0.00001) in our patients with CD. As reported in other populations, most of the patients negative for DR3, were heterozygous for DR7 and DR5 (10.34%) or DR4/DR5, DR4/DR6 (3.44%). CD was significantly correlated with the presence of HLA-DQ2 (96.55%, RR = 75.9; p < 0.00001). Correlation with CD was strongly dependent on homozygosity, 15 out of 58 (25.86%) of the patients and 4 (2.87%) of the controls being homozygotes for DQ2 (RR = 11.9; p < 0.00001). The remaining two patients were DR4-DQ3 positive. Among extended haplotypes only DR2-DQ1 was under-represented (RR = 0.3; p < 0.0033).
Conclusion: The results suggest that in Croatia CD is primarily associated with HLA-DQ2 specificities on the DR3-DQ2 haplotype.