ABCB4 and liver disorder: There have also been reports of in vitro studies using targeted pharmacotherapy with ivacaftor (initially used in the treatment of cystic fibrosis) for rescuing the function of specific missense variants of the ABCB4 (G535D, G536R, S1076C, S1176L, and G1178S)38 and ABCB11 (p.A257V, A257V, T463I, and G562D)39, 40 which are implicated in various liver diseases.