[1] Human MCC is a biotin dependent mitochondrial enzyme formed by the two subunits MCCCα and MCCCβ, encoded by MCCC1 and MCCC2 respectively.
[6] During branched-chain amino acid degradation, MCC performs a single step in the breakdown of leucine to eventually yield acetyl CoA and acetoacetate.
Point mutations and deletion events in the genes coding for MCC can lead to MCC deficiency, an inborn error of metabolism which usually presents with vomiting, metabolic acidosis, very low plasma glucose concentration, and very low levels of carnitine in plasma.
[13] In humans, MCC deficiency is a rare autosomal recessive genetic disorder whose clinical presentations range from benign to profound metabolic acidosis and death in infancy.
Patients with MCC deficiency usually have normal growth and development before the first acute episode, such as convulsions or coma, that usually occurs between the age of 6-months to 3-years.