Structure of the HLA-DR-DQ-genotype in children with coeliac disease

Abstract

Introduction. Coeliac disease is a genetically determined disease associated with the HLA-DQ2 and DQ8 genes. According to European data, these alleles are detected in more than 95% of patients. The results of earlier studies in various regions of the Russian Federation and the constituent republics have shown a lower incidence of HLA-DQ2/DQ8 in children with coeliac disease (60–80%). These data served as a basis for discussion about regional genetic features and the potential for disease development in a significant proportion of patients without DQ2/DQ8 alleles.Methods. Genetic screening was conducted on 275 children with coeliac disease. According to the results of the study, the patients were assigned to genetic risk groups.Results. HLA-DQ2/DQ8-alleles were detected in 274 children (99.6%), with 86.9% of patients having DQ2 molecule in genotype and 12.7% having DQ8 molecule. Among 239 DQ2-positive patients, 33.5% were DQ2 homozygous. The remaining DQ2-positive patients had the following HLA-DR-DQ allele distribution: DR3-DQ2/DR5-DQ7 – 8.7%, DR7-DQ2/DR5-DQ7 – 13.4%, DR3-DQ2/ DRx-DQx – 22.2%, DR7-DQ2/DRx-DQx – 2.2%. In five children the incomplete DQ2 molecule was determined, represented by DQA1*0501 allele, while in four patients DQA1*501 was associated with DQB1*0301 allele forming DR5-DQ7 molecule. We found high and significant risk alleles in 29.1% and 22.2% of cases, while moderate and low risk alleles were found in 27.3% and 21.4% of cases respectively.Conclusions: In Russian children with coeliac disease the prevalence of HLA-DQ2/DQ8 alleles corresponds to European data. Low detection frequency of HLA-DQ2/DQ8 molecules in Russian coeliac patients, which was reported earlier, may be due to peculiarities of the approach to the disease diagnostics, which do not correspond to modern Russian and international recommendations.