Ketone bodies, acetoacetate and (beta)3-hydroxybutyric acid, are produced in times of hunger/starvation. The compounds are water-soluble (and also include the spontaneous breakdown product of acetoacetate, acetone). All ketone bodies are by-products when fatty acids are broken down for energy in the liver and kidneys, and used as energy source for the heart and brain.
Ketogenesis can be impeded by inborn errors of metabolism such as Methylacetoacetyl-CoA thiolase deficiency, 3-hydroxy-3-methylglutaryl-CoA synthase deficiency and 3-hydroxy-3-methylglutaryl-CoA lyase deficiency.
In this pathway ketogenesis is visualised and linked to the different diseases. Ketogenesis can derive from leucine metabolism and fatty acid beta-oxidation and happens in the mitochondria. The enzymes ACAT1, HMGCS2, HMGCL and BDH1 play an important role during this proces.
This pathway is based on chapter 23 of the book of Blau et al. (ISBN 3642403360 (978-3642403361)), Figures 23.1 and 23.2.
For the ketolysis pathway see: [WP5195](https://www.wikipathways.org/index.php/Pathway:WP5195)