GABBR1, a component of the GABA receptor implicated in inflammation regulation, resides within the MHC extended class I region (6p21.3), influencing diseases like RA.[31] Despite specific HLA-DRB1 alleles (MHC class II) significantly contributing to RA susceptibility, potentially through their role in presenting arthritic peptides, GABBR1 might independently influence genetic susceptibility to RA due to linkage disequilibrium. The gene discussed is HLA-DRB1; the disease is rheumatoid arthritis.