GFAP and primary biliary cholangitis: The mechanistic relevance of astrocytic activation for PBC is underscored by the expression of PBC-causing genes predominantly in cell types forming the neurovascular unit.41 The PBC gene MYORG is even predominantly expressed in astrocytes.12 Nevertheless, we observed the highest GFAP serum values in our cohort in the two PBC patients with mutations in the PBC gene XPR1 (534.93 pg/mL and 936.1 pg/mL).