ABCB4 and intrahepatic cholestasis: The normality of GGT level in intrahepatic cholestasis is exceptional and tends to occur in infants or young children with some types of familial intrahepatic cholestasis, such as progressive familial intrahepatic cholestasis types 1 and 2 or in adenosine triphosphate‐binding cassette (ABCB4) mutations.