Objectives: Several associations between HLA complex and diabetes mellitus type IA were found in various groups of patients of Caucasoid population. This study was therefore prompted to be conducted in Slovak population, since any such has not yet been performed in Slovak population.
Methods: Patients suffering from DM-1A originated from all regions of Slovakia. Their age ranged from 1 to 42 years; but the criterion for including the subject to the study was the definition of diagnosis in older patients before their age of 15 (Table 1). The diagnosis was set up according to internationally accepted criteria. A total of 460 patients was typed for HLA-DQB1 alleles, among them 97 also for HLA-DQA1 and 146 for HLA-DRB1 alleles. HLA-typing was performed by a PCR-SSP method. Control group consisted of 196 (DQA), 143 (DQB1) and 130 (DRB1) unrelated blood donors aged 19-55 years old irrespective of their age or sex. The data obtained were expressed in a 2 x 2 contingency table and statistical significance was calculated by the Fisher exact test.
Results: Among 11 HLA-DQB1 alleles tested DOB1*0302 was the most frequent in DM-1A patients (30.33% vs. 5.59% in healthy subjects (HS), followed by DQB1*0201 (22.93% vs. 12.94%, respectively). In contrast, the frequency rate of DQB1*0301 (10.66% vs. 24.48%), DOB1*0602 (2.17% vs. 10.14%) and DQB1*0603 (2.5% vs. 8.39 %) were decreased in DM-1A patients. Out of 14 DQA1 alleles the highest occurrence rate showed DQA1*0301 (30.93% vs. 17.09) and DQA1*0501 (34.02% vs. 25.76%), while DQA1*0102 (8.76% vs. 16.58%) and DQA1*0201 (6.18 % vs. 13.51%7), respectively, were found to be the least frequent. Among 13 HLA-DRB1 alleles tested, the most common occurrence rates showed DRB1*03 (26.37% vs. 9.62%) and DRB1*04 (7.19% vs. 14.23%), while the least frequent alleles were DRB 1*15 (2.74% vs. 12.31%), DRB1*07 (7.19% vs. 14.23%), and DRB1*11 (2.74% vs. 20.38%). The alleles DQB1*0302 and DQA1*0301, respectively, were present in the same individual in all DRB1*04 positive patients, suggesting that they belong to the haplotype. Similar situation was observed with the alleles DQB1*0201, DQA1*0501, and DRB*0301, respectively, forming the second HLA haplotype so characteristic for DM1A.