fig1

Figure 1. Biochemical pathway illustrating role of HMG-CoA lyase in leucine catabolism and ketogenesis. Mitochondrial HMG-CoA lyase catalyses the cleavage of HMG-CoA to acetyl-CoA and acetoacetate, the common final step of ketogenesis and leucine degradation, resulting in a diagnostic urinary organic acid pattern, (elevated 3-hydroxy-3-methylglutaric, 3-methylgutaconic, 3-methylglutaric, and 3-hydroxyisovaleric acids) with absence of ketonuria.