Islet-cell antibodies (ICA-CFICA) and HLA genotypes in 107 IDD patients and their first-degree relatives.

The prevalence of ICA and CFICA in relation to HLA-DR genotypes was analyzed in 107 insulin-dependent diabetic (IDD) patients with a duration of IDD ranging from onset to 30 years, and 247 nondiabetic first-degree relatives. In 46 patients tested at onset of IDD, the prevalence of ICA and of CFICA was 61 and 50%, respectively; with the longer duration of IDD, the prevalence of CFICA decreased more rapidly than that of ICA. No significant association was observed between ICA and any HLA allele in patients tested from onset till 2 years after onset. However, a higher prevalence of ICA was found in DR3 positive patients with a duration of IDD of more than 2 years (p less than 0.02). Among the healthy relatives, the prevalence of ICA was 7% in parents and 13% in siblings; one out of 101 siblings had CFICA. No association was found between ICA and any HLA marker. The presence of ICA in sibs was independent of the number of haplotypes they shared with the IDD proband: among the 13 ICA-positive healthy sibs, one shared 2 haplotypes, nine shared 1 haplotype and three shared no haplotype with the proband, which is not different from the random distribution.