Role of human-tissue transglutaminase IgG and anti-gliadin IgG antibodies in the diagnosis of coeliac disease in patients with selective immunoglobulin A deficiency.

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Selective IgA deficiency is associated with coeliac disease , and studies have shown an increased prevalence of coeliac disease in these patients ranging from 0 .71 to 30 .7 %, depending on the test used for screening .To determine the sensitivity of IgG anti-gliadin-antibodies and of IgG human-tissue-transglutaminase for diagnosing coeliac disease and assessing its prevalence in subjects with IgA deficiency .We tested serum samples from 126 IgA-deficient children (66 female , median age : 10 .8 years ).All samples were analysed to measure IgG anti-gliadin-antibodies and IgG anti-human-tissue-transglutaminase . Patients testing positive to either test underwent intestinal biopsy . Subjects testing positive for IgG anti-human-tissue-transglutaminase underwent genetic testing for the human leucocyte antigen heterodimer .Twenty -seven of 126 subjects tested positive for IgG anti-gliadin-antibodies (five of whom tested positive also for IgG anti-human-tissue-transglutaminase ) and 18 (including the aforementioned five ) for IgG anti-human-tissue-transglutaminase . Intestinal biopsy was performed in 37 of the 40 patients who tested positive (three subjects refused ). Eleven had positive intestinal biopsies all of whom tested positive for IgG anti-human-tissue-transglutaminase , but only five of these tested positive also for IgG anti-gliadin-antibodies . All 22 patients testing positive for anti-gliadin-antibody alone had normal intestinal mucosa . All the patients who tested positive for IgG anti-human-tissue-transglutaminase and underwent genetic screening (15 /18 ) had the coeliac-related human leucocyte antigen . Overall , coeliac disease was diagnosed in 11 of the 126 subjects with IgA deficiency (8 .7 %).The prevalence of coeliac disease in subjects with total IgA deficiency was 8 .7 %. Assay of IgG anti-human-tissue-transglutaminase can be recommended for screening coeliac disease in IgA-deficient subjects .