PRTN3 and rheumatoid arthritis: Association with HLA-DRB1*03 was previously found in minor studies for ACPA-negative RA, which also suggests a link to this haplotype with the HLA-DRB3 gene or more generally with ancestral haplotype (AH) 8.1, with HLA-B*08 and HLA-DRB1*03 involved [35].