ABCB4 and Alagille syndrome: Could single-gene analysis for JAG1, NOTCH2 (Alagille syndrome), SERPINA 1(A1ATd), DCDC2 (isolated neonatal sclerosing cholangitis), and ABCB4 (PFIC3) still be used to exclude these intrahepatic diseases and avoid diagnostic errors in the first step of the investigation?