Auto-immunity in children with diabetes mellitus and in their relatives.

Islet cell antibodies (ICA-IgG and complement-fixing-ICA), parietal cell antibodies (PCA), intestinal epithelial cell antibodies (IECA), thyroglobulin (TgA) and thyroid microsomal antibodies (MsA), antinuclear (ANA) and reticulin antibodies (RA), were studied in 55 insulin-dependent diabetic patients (30 males and 25 females), aged 2-19 years with diabetes from a few days up to 14 years. In 58% of the diabetics one or more autoantibodies were found: ICA-IgG (31%), CF-ICA (16%), PCA (34%), TgA (9%), MsA (9%), ANA (13%), RA (2%). Autoantibodies were significantly more frequent in females (76%) than in males (43%) (P less than 0.025). ICA-IgG, CF-ICA, PCA, ANA were significantly more frequent in patients than in controls. The frequency of ICA-IgG and CF-ICA was significantly higher during the first 3 years of disease than afterwards (P less than 0.001); a similar pattern was observed for PCA, TgA, MsA. Of the 87 parents and 30 siblings screened for ICA-IgG, CF-ICA, PCA, IECA, TgA, MsA, ANA and RA, 42 (44%) had one or more autoantibodies, which were more frequent in females than in males. Seven relatives (6%) were ICA-IgG positive (four mothers, two fathers and one brother), and only one mother, ICA-IgG negative, was CF-ICA positive. Other autoantibodies were also more frequent in parents than in controls. Autoantibody-positive relatives have been asymptomatic up to now.