HLA associations in small-duct compared with large-duct primary sclerosing cholangitis - Naess, S; Anmarkrud, J; Bjornsson, E; Al Mamari, S; Juran, B; Lazaridis, K; Chapman, R; Bergquist, A; Schrumpf, E; Lie, B; Boberg, K; Karlsen, T; et al. (2012)