In agreement with previous data, both GFAP and neurofilaments correlated with the age of probands (Supplementary Fig. 1).30-32 However, age was not a confounder when comparing PBC and controls, and both groups matched concerning age and sex (P-value controls versus PBC = 0.673; P-value asymptomatic versus symptomatic versus controls = 0.687; P-value no identified mutation versus genetic versus controls = 0.413; Supplementary Table 4). This evidence concerns the gene GFAP and primary biliary cholangitis.