While specific HLA-DRB1 alleles (MHC class II) contribute strongly to RA susceptibility, possibly due to their role in presenting arthritogenic peptides, GABBR1 polymorphisms are not in linkage disequilibrium with these alleles (within publicly available HapMap data) as is expected given the 3 Mb distance between the two loci. Here, GABBR1 is linked to rheumatoid arthritis.