ABCB4 and liver disorder: Studies on the genotypic-phenotypic correlation of ABCB4-related cholestatic liver diseases [15–18] suggested that those with compound heterozygous or homozygous ABCB4 pathogenic mutations have a higher proportion of progression to cirrhosis and end-stage liver disease, whereas those with heterozygous mutations usually have mild lesions or even no symptoms [19].