Although there is a clear genetic pre-disposition to the likelihood of developing PBC, none of the genetic variants predisposing to PBC are in themselves abnormal (Mells et al., 2011; Cordell et al., 2015) and the odds-ratios associated with the most prominent genetic variants (e.g IL12RB2 with an odds ratio 1.52 [95% CI 1.39–1.67] (Mells et al., 2011) are relatively low. The gene discussed is IL12RB2; the disease is primary biliary cholangitis.