Comparative analysis of organ-specific autoantibodies and celiac disease-associated antibodies in type 1 diabetic patients, their first-degree relatives, and healthy control subjects

OBJECTIVE - In type 1 diabetes the coexistence with other endocrine disease s and organ-specific autoantibodies has been frequently reported leading to the concept of autoimmune polyendocrine syndrome (APS). In addition, an as sociation of type 1 diabetes with celiac disease has been described. These disorders share a similar genetic background, and first-degree relatives of type 1 diabetic patients may also be affected significantly Screening for specific antibodies allows early diagnosis of these disorders. RESEARCH DESIGN AND METHODS - In the present cross-sectional study, we anal yzed sera from 197 recent-onset type 1 diabetic patients at the time of dia gnosis, 882 first-degree relatives, and sera of 150 healthy control subject s for prevalence and co-occurence of the following antibodies (method): ins ulin autoantibodies (radioimmunoassay); GAD and IA-2 antibodies (radioligan d assay); islet cell antibody anti-adrenal cortex antibodies, and anti-gast ric parietal cell antibodies (indirect immunofluorescence); anti-thyroglobu lin and anti-thyroid peroxidase antibodies; and gliadin IgG/A and tissue-tr ansglutaminase IgA (enzyme-linked immunosorbent assay). RESULTS - The overall frequency of gastric patietal cell antibodies and adr enal antibodies did not differ significantly among groups. In contrast, typ e 1 diabetes-associated antibodies and thyroid antibodies were significantl y more frequent both in recent-onset type 1 diabetic patients and in the gr oup of first-degree relatives (P < 0.05). The prevalence of gliadin IgG/IgA and transglutaminase IgA was significantly higher in the group of recent-o nset type 1 diabetic patients (P < 0.05), but the difference between first- degree relatives and control subjects did not reach statistical significanc e. Focusing on the coexistence of antibodies, the group of recent-onset typ e 1 diabetic patients presented with 27.4% of the subjects testing antibody -positive-specific for two or more of the envisaged disorders (i.e., type 1 diabetes, autoimmune thyroiditis, and celiac disease) compared with 3.1% i n the group of first-degree relatives and 0 of 150 in the control populatio n (P < 0.05). CONCLUSIONS - We conclude that, in an active case-finding strategy, recent- onset type 1 diabetic patients should be routinely screened at least for co ncomitant autoimmune thyroid disease and additionally for celiac disease. S creening in their first-degree relatives should include at a minimum the se arch for thyroid autoimmunity in addition to screening for pre-type 1 diabe tes.