Identification of an HLA-DQ beta-chain related genomic sequence associated with insulin-dependent diabetes.

Restriction fragment length polymorphism detected by a cDNA probe for an HLA-DQ beta-chain gene has revealed a HLA-DR4 linked BamH1 3.7 kb fragment which is rarely found among insulin-dependent diabetic patients. The present analysis demonstrates that the BamH1 3.7 kb fragment present on a HLA-DR4 positive chromosome in a healthy individual contains coding sequences for an HLA-DQ beta-chain gene and that the absence of this fragment among HLA-DR4 positive insulin-dependent patients is due to the loss of a BamH1 restriction within an intervening sequence.