TJP2 and cystic fibrosis: Figure 3 shows the time trend of use of LB and advanced molecular testing as part of our diagnostic work up of IC during the study period. The genetic causes of cholestasis diagnosed during level 1 of assessment included: Alagille syndrome (n = 14), CF (n = 8), PFIC2 (n = 8), DJS (n = 31), TJP2 gene mutation (n = 1), MYO5B gene mutation (n = 3), BASD (n = 17), ARC syndrome (n = 2), mitochondrial hepatopathy (n = 15), galactosemia (n = 13), tyrosinemia (n = 6), primary adrenal insufficiency due to MCT2R gene mutation (n = 1), and familial HLH (n = 7).