Prevention trials for IDDM require the evaluation of predictive markers in risk populations. The aim of this study was to determine sensitivity, specificity and relative risk of immmunological and genetic analyses in patients with recent onset of diabetes, and determine their prevelance in first grade relatives with higher risk to develope IDDM. We studied 64 patients with IDDM, 64 sex and age matched controls without personal or familial history of autoinmune disease (mean age 10,2 ± 3,8 yr), and 41 siblings of patients (mean age 11,0 ± 5,2 yr). Assays were performed using fasten serum samples in the control group and siblings; as for the diabetic group, samples were obtained within 72 hours after starting insulin therapy. Markers were detected as follow: IAA by radiobinding assay, GAD antibodies by immunoprecipitation with 35 S-MetGAD expressed in reticulocytes, ICA by indirect immunofluorescence and DQB alleles by DNA typing.Table

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One sibling was both A-GAD + 2nd ASP-/ASP-. Conclusions: Sensitivity and specificity of our assays are consistent with reported results. All diabetic patients proved negative for protective alleles. Presence of DQB1 *302/0201 in siblings was significantly lower than in diabetic children.