Human leucocyte antigen genotyping in celiac disease: Reasons for inappropriate use

Background: Celiac disease (CD) is an autoimmune enteropathy, which may need further Human Leukocyte Antigen (HLA) testing beyond autoantibodies for diagnosis due to the necessity of lifetime gluten restriction. HLA genotyping test is useful in certain scenarios for CD diagnosis and screening. The aim of this study was to evaluate the reasons for inappropriate requesting of HLA testing. Methods: One hundred and fifteen patients, who had been tested for CD-related HLAs, were included in this study. Final diagnosis, indication of HLA test, serological and histopathological findings were re-evaluated to determine the inappropriate usage of HLA testing. Results: Among all patients, 44 (38.2%) were diagnosed with CD according to their genotyping results. The frequency of DQ 2.5, DQ8 and DQ2.2 haplotypes among these patients was 57.2%, 28.2%, and 14.3%, respectively. HLA test was performed inappropriately in 35 (30.4%) of patients. The most common reason was serology and pathological findings of patients were already conclusive as CD in 15 (42.9%) patients. Serology negative patients were tested without any supporting finding of CD in 11 (31.4%) patients. Last identified reason was that patients whose serology and intestinal biopsy were not conclusive as CD in 9 (25.7%) patients. Conclusions: Before requesting HLA typing test, patient’s data should be thoroughly evaluated to confirm the need for test.