Review article: liver disease in adults with variants in the cholestasis‐related genes ABCB11, ABCB4 and ATP8B1

Individuals with variants in ABCB11 rarely develop cholestasis until BSEP function dips below a threshold, which is also affected by other factors (e.g., drugs, hormones). However, variants in ABCB4 and consequent reduction in MDR3 protein, have a more linear dose-response curve. In individuals with an ABCB11 variant, medications known to reduce BSEP activity should be used cautiously; they should be monitored during pregnancy for ICP; and first-degree relatives should be counselled and screened. No proven management strategy exists, although ursodeoxycholic acid may be beneficial. Further work is needed to define the genotype-phenotype correlation and natural history, and to evaluate the penetrance.