GWAS and animal model studies have implicated MHC molecules, interferon-gamma signalling and apoptosis in the development of Graves’ disease (Morshed and Davies, 2015; Okada et al., 2015; Smith and Hegedüs, 2016), rheumatoid arthritis (Castañeda-Delgado et al., 2017; Okada et al., 2019), and chronic hepatitis B infection (Ebert et al., 2015; Zhu et al., 2016). Here, HLA-C is linked to chronic hepatitis B virus infection.