A 61-year-old woman shows joint stiffness and pain along with a positive anti-cyclic citrullinated peptide. What is a known genetic marker linked to her condition?

The presence of a positive anti-cyclic citrullinated peptide (anti-CCP) antibody in this 61-year-old woman suggests that she is likely suffering from rheumatoid arthritis (RA), an autoimmune condition characterized by joint stiffness and pain. One of the known genetic markers associated with rheumatoid arthritis is Human leukocyte antigen DRB1 (HLA-DRB1). This gene is part of the major histocompatibility complex (MHC) and plays a crucial role in immune system functioning.

Certain alleles of the HLA-DRB1 gene have been linked to an increased susceptibility to rheumatoid arthritis, specifically those that are associated with the presentation of citrullinated peptides to T-cells, which is a key mechanism in the pathogenesis of RA. Thus, the presence of specific HLA-DRB1 alleles not only aids in predicting an individual’s risk for developing rheumatoid arthritis but also correlates with the severity of the disease.

While other genetic markers exist for various autoimmune diseases, the link between HLA-DRB1 and rheumatoid arthritis is particularly well-established, making this the most relevant choice for the condition described.