What gene family includes HLA-DRB1 & DRw4, implicated in rheumatoid arthritis?

• A. IL receptor
• B. TNF receptor
• C. COL genes
• D. MHC

Answer: (D)

Genetic susceptibility to rheumatoid arthritis is tied to the major histocompatibility complex, particularly the class II region that encodes HLA molecules responsible for presenting antigens to CD4+ T cells. HLA-DRB1 is a key gene in this region, and DRw4 is a historical serotype within DRB1—both belong to the MHC. This gene family, the MHC, governs antigen presentation and influences autoimmune risk, which is why it’s the correct classification. Other gene families, such as IL receptors, TNF receptors, or collagen (COL) genes, do not reside in this region and are not the primary loci implicated by HLA-DRB1 or DRw4 in rheumatoid arthritis.