Screening for coeliac disease in families of adults with Type 1 diabetes based on serological markers

The prevalence of coeliac disease (CD) in the adult population is unknown b ecause silent and latent stages do exist. Type 1 diabetes mellitus may be a ssociated with CD because of common genetic background and/or shared pathog enetic mechanisms. We investigated 74 adults with type 1 diabetes (32 +/- 1 1 yr, disease duration 13 +/-9 yr), 69 parents of diabetic probands (56 +/- 10 yr), 59 siblings (30 +/- 11 yr) and 50 healthy controls (35 +/- 10 yr) for the presence of circulating islet cell antibodies (ICA), anti-glutamic acid decarboxylase antibodies (GADA65), anti-gliadin immunoglobulins A and G (IgA- and IgG-AGA). All patients with raised AGA, performed also IgA anti -endomysium antibody (EmA) indirect immunofluorescence assay. Samples were positive for ICA in 19 diabetics (26%), 4 parents (6%), 4 siblings (7%), 0 controls (p <0.001); for GADA in 34 diabetics (46%), 4 parents (6%), 1 sibl ing (2%), 0 controls (p <0.001). Twenty-five diabetic patients (34%), 10 pa rents (14%), 5 siblings (8%), 3 controls (6%) (p <0.001) had raised IgA-AGA (>4.4 mg/l). Four diabetic patients (5%), 5 parents (7%), 0 siblings (0%), 4 controls (8%) had raised IgG-AGA (> 18 mg/l). Both IgA- and IgG-AGA were detected in 1 diabetic and 2 parents. The prevalence of ICA, GADA, and IgA -AGA positivity in Type 1 diabetes patients was significantly higher than i n controls p <0.001). Finally, 50 AGA-positive subjects performed EmA test: only 2 of them resulted EmA-positive, a diabetic patient and a sibling. Th e patient with Type 1 diabetes had a small-bowel biopsy specimen consistent with CD and, as sole evidence of malabsorption, sideropenic anaemia. EmA-p ositive sibling also showed severe iron deficiency, yet refused endoscopy. We conclude that: 1) CD cannot be diagnosed on the basis of associated IgA- and IgG-AGA alone. Nevertheless, detection of such antibodies is useful, i n combination with EmA, in screening for endoscopic biopsy; 2) too high rat e of detection of IgA-AGA in Type 1 diabetic patients in comparison with ot her groups excludes a false positivity of the test itself, while suggests a pathogenetic association of both immunological disorders, perhaps related to abnormal gamma delta TCR-bearing intraepithelial lymphocytes. (C) 2001, Editrice Kurtis.