For instance, Gonzalez-Gay et al. conducted research within a Spanish cohort and identified associations between YORA and the DRB1/04 allele, and between EORA and the DRB1/01 allele.24 Their findings revealed that the shared epitope (SE, an amino acid sequence commonly found in certain alleles of the HLA-DRB1 gene), particularly associated with DRB1/04, was significantly more frequent in YORA patients, with a frequency of 77.8% compared to 37.1% in EORA. This genetic distinction suggests that DRB1/04 plays a stronger role in disease susceptibility and severity among younger RA patients. Here, HLA-DRB1 is linked to rheumatoid arthritis.