Intrahepatic cholestasis induced by drug toxicity, bile salt export pump (BSEP) deficiency, or pregnancy frequently causes cholestatic liver damage, which ultimately may lead to liver fibrosis and cirrhosis.
In the present issue of Clinical Science, Iwata and co-workers report an association between a variant of a gene regulating bile acid levels, ABCB11 1331T>C (where ABCB11 encodes ATP-binding cassette, subfamily B, member 11), and the progression to cirrhosis in patients with HCV, but not in fatty liver patients.
Progressive familial intrahepatic cholestasis, type 2 (PFIC2), characterized by cholestasis in infancy that may progress to cirrhosis, is caused by mutation in ABCB11, which encodes bile salt export pump (BSEP).
The common ABCB11 1331CC genotype, which is present in 40% of HCV patients and renders the carrier susceptible to increased bile acid levels, is associated with cirrhosis.
An absence of BSEP from the canalicular membrane causes cholestasis and leads to liver cirrhosis, which may necessitate liver transplantation in early childhood.
Thus, it has been recognized that while mutations in the gene encoding BSEP are responsible for a subgroup of progressive familial cholestasis (progressive familial intrahepatic cholestasis subtype 2), a pediatric cholestatic disorder that may progress to cirrhosis, defective expression or function of BSEP may underlie some forms of drug-induced cholestasis.