Mutations of AKR1D1 lead to severely reduced to completely absent urinary 5β-reduced steroid excretion and hepatic failure, as AKR1D1 is essentially involved in hepatic bile acid synthesis, but no other clinical manifestations (Gonzales et al., 2004, Lemonde et al., 2003, Palermo et al., 2008). Here, AKR1D1 is linked to liver failure.