Background and aims: Celiac disease is characterized by an inappropriate T-cell-mediated response to gluten in small bowel in genetically predisposed individuals, carriers of the DQ2 and/or DQ8 haplotypes of the human leukocyte antigen. The aim of our study was to asses HLA typing in adult patients with celiac disease, in their first degree relatives and in a healthy control group.
Methods: We conducted a prospective observational study on three cohorts: 117 patients diagnosed with celiac disease, 41 first-degree relatives of celiac patients and 57 asymptomatic healthy volunteers. Low resolution HLA typing for DQ alleles was performed in all study subjects with DNA extracted from peripheral blood, using SSP HLA-DQB1 kit (Innotrain Diagnostik GmbH, Germany). Next Generation Sequencing (NGS) was used only in 18 patients for typing confirmation of DQB1 and DQA1 loci and whole gene sequencing.
Results: Prevalence of HLA-DQ2 was significantly higher in the CD group compared to the healthy subjects group (95.6% vs 29.8%, p <0.001), with no statistically significant differences in HLA-DQ8 and combined HLA-DQ2/DQ8 prevalences.Several HLA DQA1 and DQB1 alleles (HLA-DQA1* 05:01, HLA-DQB1*02:01, HLA-DQB1*02:02) and haplotypes (DQA1*02:01-DQB1*02:02,DQA1*05:01-DQB1*02:01) were strongly associated with celiac disease in our group: OR 4.28, 4.28, 4.67 and 5.43 and 4.28 respectively. Predominantly, patients presented with typical symptoms and iron deficiency anemia. 95.5% of them had histological Marsh type modifications ≥3a. A relatively poor response to gluten-free diet was observed and 9.4% developed complications (refractory celiac disease, enteropathy-associated T cell lymphoma, intestinal adenocarcinoma), with a death rate of 6.8%. 23% associated other autoimmune diseases.Screening adherence for 1st degree relatives was very low: only 16%. Familial screening diagnosed 4 cases of asymptomatic celiac disease. 32 relatives (78%) had HLA-DQ2 haplotype, 5 carried HLA-DQ8, 4 didn't carry any risk haplotype.
Conclusions: This study demonstrated a higher prevalence of the HLA-DQ2 genotype in patients with celiac disease compared to the healthy population but not of HLA-DQ8 or combined HLA-DQ2/DQ8. Alleles HLA-DQA1* 05:01, HLA-DQB1*02:01, HLA-DQB1*02:02 and haplotypes (DQA1*02:01-DQB1*02:02,DQA1*05:01-DQB1*02:01) were strongly associated with celiac disease in our cohort.