ATP8B1 and progressive familial intrahepatic cholestasis: Heterozygotes variants in the ATP8B1 gene on chromosome 18q21, except intrahepatic cholestasis of pregnancy 1 (ICP1, OMIM 147480), can also cause progressive familial intrahepatic cholestasis 1 (PFIC1, OMIM 211600) and benign recurrent intrahepatic cholestasis 1 (BRIC1, OMIM 243300).1