The level and the persistence of islet cell antibodies in healthy schoolchildren are associated with polymorphic residues of the HLA-DQ beta chain.

Cytoplasmic islet cell antibodies (ICA) were determined in a group of non-diabetic Caucasian schoolchildren (n = 4208). The prevalence rate for ICA positivity was 1.05 per cent (95 per cent confidence interval: 0.8-1.4 per cent). Analysis of HLA risk factors revealed that HLA-DRB1*03 (p less than 0.01), HLA-DRB1*04 (p less than 0.01) and HLA haplotypes with non-charged amino acids (non-Asp) at codon 57 of the HLA-DQ beta (p less than 0.01) chain were significantly increased when compared to controls. High levels of islet cell antibodies, i.e. Juvenile Diabetes Federation units (JDF units) equal to or greater than 30 JDF units were found to be associated with amino acids other than aspartic acid at codon 57 of the DQ beta chain molecule. Also the persistence of circulating ICA was found to be associated with non-Asp homozygosity of the proband (p less than 0.03).