Overview

Malonyl-CoA decarboxylase deficiency is a rare metabolic disorder that impairs the body’s ability to convert specific fats into usable energy. This condition generally presents its symptoms in early childhood. In nearly all cases, affected children experience developmental delays. Additionally, symptoms may include poor muscle tone (hypotonia), seizures, digestive issues such as diarrhea and vomiting, as well as episodes of low blood sugar (hypoglycemia). A notable complication is cardiomyopathy, a heart condition that weakens and enlarges the heart muscle, often seen in individuals with this deficiency.

Prevalence

Malonyl-CoA decarboxylase deficiency is extremely uncommon, with fewer than 30 known cases documented worldwide.

Underlying Causes

This condition is caused by mutations in the MLYCD gene. The MLYCD gene encodes the malonyl-CoA decarboxylase enzyme, which plays a crucial role in the metabolism of fatty acids—substances many tissues, including the heart, rely on for energy production.

Mutations in the MLYCD gene reduce or completely eliminate the function of this enzyme, disturbing the balance between fatty acid creation and breakdown. As a result, fatty acids accumulate instead of being converted into energy. This imbalance leads to symptoms such as hypoglycemia and cardiomyopathy. Additionally, byproducts from faulty fatty acid processing contribute to various manifestations of this condition.

Further Information on Related Gene

• MLYCD

Inheritance Pattern

Malonyl-CoA decarboxylase deficiency follows an autosomal recessive inheritance pattern. This means both copies of the implicated gene must carry mutations for a person to be affected. Typically, the parents of an affected child each carry one mutated copy of the gene; however, they do not show any symptoms of the condition.

Alternate Names for This Disorder

• Malonyl-coenzyme A decarboxylase deficiency
• Malonic aciduria
• MCD deficiency
• Malonyl-CoA decarboxylase deficiency

Additional Resources & Support

Genetic Testing Information

• Genetic Testing Registry: Deficiency of malonyl-CoA decarboxylase

Genetic and Rare Diseases Information Center

Patient Support and Advocacy

• National Organization for Rare Disorders (NORD)

Clinical Trials

• ClinicalTrials.gov

Catalog of Genes and Diseases from OMIM

• Malonyl-CoA Decarboxylase Deficiency

Scientific Research on PubMed

• PubMed

Scientific References

• de Wit MC, et al. Brain abnormalities in a patient with malonyl-CoA decarboxylase deficiency. Mol Genet Metab. 2006 Feb;87(2):102-6. DOI: 10.1016/j.ymgme.2005.09.009. Link to PubMed
• FitzPatrick DR, et al. The molecular basis of malonyl-CoA decarboxylase deficiency. Am J Hum Genet. 1999 Aug;65(2):318-26. DOI: 10.1086/302492. Link to PubMed
• Sacksteder KA, et al. MCD encodes both peroxisomal and cytoplasmic malonyl-CoA decarboxylase. J Biol Chem. 1999 Aug;274(35):24461-8. DOI: 10.1074/jbc.274.35.24461. Link to PubMed
• Salomons GS, et al. Characterization of nine new patients with malonyl-coenzyme A decarboxylase deficiency. J Inherit Metab Dis. 2007 Feb;30(1):23-8. DOI: 10.1007/s10545-006-0514-6. Link to PubMed