BAs also play a major role in sex differences in liver pathologies, including cholestasis and fibrosis, as the multidrug resistance protein 2 (Mdr2) KO female mice have a more hydrophobic BA pool and higher levels of taurocholate in the bile when compared to their male counterparts, which is associated with more severe liver injury.43 The gene discussed is ABCB4; the disease is cholestasis.