PRTN3 and rheumatoid arthritis: A later study of independent European cohorts suggested association of ACPA-negative RA with Leu at position 67 of HLA-DRB1, with a risk effect of 1.38 [34]; this result is likely due to contamination of the RA group with unrecognized ACPA-positive individuals since this amino acid is characteristic for all SE allele-positive haplotypes, including *14:02, and should be regarded with caution.