CBS and hyperinsulinemic hypoglycemia, familial, 4: The mechanism of CBS deficiency-associated liver steatosis and liver dysfunction may be related to the accumulation of hepatotoxic homocysteine and/or the lack of cytoprotective cystathionine and H2S generation in the liver, but additional mechanisms (e.g., a dysregulation of thiolase, a key enzyme in beta-oxidation of fatty acids [110] as well as dysregulation of various ATP-binding cassette transporters and nuclear hormone receptors involved in liver lipid homeostasis [111]) have also been implicated.