RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISMS IN HLA-DR4-DQ3 HAPLOTYPES ASSOCIATED WITH RHEUMATOID-ARTHRITIS

Restriction fragment length polymorphism (RFLP) patterns were studied in serologically confirmed DR4-DQ3 positive patients with rheumatoid a rthritis by Southern blot analysis using full length cDNA probes speci fic for DRB, DQA and DQB hybridized with genomic DNA digested with inf ormative restriction endonucleases. The RFLP patterns correlated with serology confirming all patients to be DR4+ve. The DQB10302 (DQ8) all ele identified by 12.0kb BamHI, 3.3kb Hind III and 1.8kb Taql fragment s was present in all patients suggesting them to be DR4-DQB10302. Hyb ridization of Taq 1 and PVU II digested genomic DNA with DQA cDNA prob e revealed four informative RFLP patterns. While three or them correla ted with known DR4 subtypes, one was a new polymorphism observed speci fically in Indian patients with rheumatoid arthritis. The study furthe r indicated that two of the several known subtypes of DR4, viz., DRB1 0401-DW4-DQB10302 and DRB1*0404-DW14-DQB1*0302 may be implicated in s usceptibility to rheumatoid arthritis in the Indian population.