Nonetheless, more recently, a single nucleotide polymorphism (SNP) involving a substitution of histidine or tyrosine for asparagine at position 9 in the alpha chain peptide-binding groove of class I HLA-B molecule (HLA-B*8-Asp9), corresponding to the HLA-B*08:01 allele, has been associated with a higher risk for ACPA-positive RA [17, 25]. This evidence concerns the gene PRTN3 and rheumatoid arthritis.