HLA‐DQB102 Dose Effect on RIA Anti‐tissue Transglutaminase Autoantibody Levels and Clinicopathological Expressivity of Celiac Disease

ABSTRACT 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 RIA tTGAb 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 are 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.