ABCB11 and progressive familial intrahepatic cholestasis type 2: Furthermore, our group and Gonzales et al. reported recently that 4PB therapy restored decreased BSEP expression, improved liver functions in histological and biochemical analysis, and relieved intractable pruritus in patients with PFIC type 2 (PFIC2), an inherited autosomal recessive liver disease caused by mutations in BSEP[15,16].