Protective effect of an ERAP1 haplotype in ankylosing spondylitis: Investigating non-MHC genes in HLA-B27-positive individuals - Bettencourt, B.F.; Rocha, F.L.; Alves, H.; Amorim, R.; Caetano-Lopes, J.; Vieira-Sousa, E.; Pimentel-Santos, F.; Lima, M.; Porto, G.; Branco, J.C.; Fonseca, J.E.; Bruges-Armas, J. (Rheumatology (United Kingdom), 2013)