Epidemiology and Immunogenetic Background of Islet Cell Antibody–Positive Nondiabetic Schoolchildren: Ulm-Frankfurt Population Study

Islet cell antibodies (ICAs) were determined in a large cohort of white nondiabetic schoolchildren (n = 4287) from a homogenous population in southern Germany. The prevalence of ICA levels ≥5 Juvenile Diabetes Foundation (JDF) U was 1.05% (95% confidence interval 0.8–1.4%). Analysis of HLA-DRβ and -DQβ alleles revealed that the specificities found to be increased in insulin-dependent (type I) diabetic subjects with the same ethnic background were also associated with ICA positivity in the nondiabetic schoolchildren. HLA-DR3 (P < 0.01) and -DR4 (P < 0.01) phenotypes and absence of Asp residue (P < 0.01) at codon 57 of the HLA-DQ β-chain were significantly increased in ICA⁺ compared with control subjects. High levels of ICAs, which were categorized as either ≥17 or ≥30 JDF U, were found to be associated with amino acids other than Asp at position 57 of the HLA-DQ β-chain. No association of ICA level was found for HLA-DR phenotypes.