HLA-DQB1*02 dose effect on RIA anti-tissue transglutaminase autoantibody levels and clinicopathological expressivity of celiac disease

Objectives: Celiac disease is an autoimmune enteropathy caused by gluten ingestion in genetically susceptible individuals. Anti-transglutaminase autoantibody (tTGAb) assay is useful to detect candidates undergoing intestinal biopsy. Our aim was to investigate whether the DQB1*02 allele could influence tTGAb titers and the clinicopathological expressivity of the disease. Methods: A total of 124 patients with celiac disease, tested for RIAtTGAb at diagnosis, were typed for HLA-DRB1,-DQA1, and -DQB1 genes and divided according to the number of DQB1*02 alleles: group 1, homozygous; group 2, heterozygous; group 3, negative. Results: The mean of tTGAb indexes was significantly higher in group 1 patients than in group 2 (P < 0.02) and group 3 patients (P < 0.01). Patients with at least 1 DQB1*02 allele showed more often a typical CD and diffuse histological lesions than did patients in the other groups. Conclusions: The study demonstrates that tTGAb titers arc HLA-DQB1*02 dose dependent, with significantly higher levels in homozygous individuals. Moreover. individuals with at least 1 HLA-DQB1*02 allele tend to have a more expressed clinical and histological form of celiac disease.