Comparison between HLA-DRB and DQ DNA sequences and classic serological markers as Type 11 (insulin-dependent)diabetes mellitus predictive risk markers in the Spanish population

Abstract

The question of HLA susceptibility to Type 1(insulin-dependent) diabetes mellitus remains unresolved. In the present study, 127 diabetic patients and 177 unrelated control subjects have been analysed for their class I and class II serological antigens, class II (DR, DQ) DNA restriction fragment length polymorphisms and DQA1 and B1 exon-2 nucleotide sequences and their corresponding amino acid residues. By using the aetiologic fraction (δ) as an almost absolute measure of the strongest linkage disequilibrium of an HLA marker to the putative Type 1 diabetes susceptibility locus, it has been found that the strength of association of the HLA markers may be quantified as follows: DR4 < DR3 < DR3 or DR4 < non-Aspartate 57 ßDQ and Arginine 52 αDQ