Malonic Acidemia

Other Names


Malonyl-CoA decarboxylase deficiency

Malonyl-coenzyme A decarboxylase deficiency

Malonic aciduria



Diagnosis Coding

E71.39, other disorders of fatty-acid metabolism

Disorder Category

An organic acidemia



Elevated C3-DC (acylcarnitine)

Tested By

Tandem mass spectrometry (MS/MS); sensitivity=NA; specificity=NA


Insufficient malonyl-CoA decarboxylase results in the accumulation of malonic acid and its derivatives in the blood. Malonic acid inhibits fatty acid oxidation, resulting in hypoglycemia, and potentially causing cardiomyopathy. Treatment involves carnitine supplementation, a low-fat diet supplemented with medium chain triglycerides (oxidation is not inhibited by malonic acid), and avoidance of fasting. [Wightman: 2003]


Fewer than 30 cases have been reported. [Genetics: 2017]


Autosomal recessive

Prenatal Testing

DNA testing by amniocentesis or CVS

Clinical Characteristics

With treatment, some of the sequelae may be prevented or ameliorated. Without treatment, episodes of hypoglycemia and metabolic acidosis may lead to delayed development, hypotonia, seizures, and cardiomyopathy. While symptoms may present within the first few weeks of life, symptoms are more likely to develop in older infants and children. Symptoms may be triggered by fasting and illness. Developmental delays and hypotonia can be seen even with optimal treatment and without any episode of decompensation.

Initial symptoms/signs may include:
  • Hypotonia
  • Cardiomyopathy
  • Seizures
  • Vomiting
  • Poor feeding
  • Diarrhea
  • Lethargy
  • Hypoglycemia
  • Lactic acidosis

Follow-up Testing after Positive Screen

Quantitative plasma acylcarnitine profile, urine organic acids (elevated malonic acid)

Primary Care Management

Upon Notification of the + Screen

If the Diagnosis is Confirmed

  • Educate the family regarding signs, symptoms, and the need for urgent care when the infant becomes ill.
  • Support implementation and maintenance of a high-carbohydrate, low-fat diet with medium chain triglyceride supplements. Oral L-carnitine is indicated.
  • Promptly treat infections, fever, and gastroenteritis with IV fluids containing glucose and admit to hospital.
  • For those identified after irreversible consequences, assist in management, particularly with developmental and educational interventions.

Specialty Care Collaboration

Provide initial consultation and ongoing collaboration, particularly for dietary management. Facilitate genetic counseling for the family.


Information & Support

For Professionals

Malonic Aciduria (OMIM)
Information about clinical features, diagnosis, management, and molecular and population genetics; Online Mendelian Inheritance in Man, authored and edited at the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine

For Parents and Patients

Malonic Aciduria (MedlinePlus)
Information for families that includes description, frequency, causes, inheritance, other names, and additional resources; from the National Library of Medicine.

Baby's First Test: Malonic Aciduria (Genetic Alliance)
Information about early signs, follow-up testing, treatment, accessing care, and expected outcomes. Provides links to support services.

Organic Acidemia Association (OAA)
A nonprofit organization that provides information, support, events, connections with other parents, a discussion board, and nutrition and recipe ideas.


ACT Sheet for Malonic Aciduria (Elevated C3-DC) (ACMG) (PDF Document 347 KB)
Contains short-term recommendations for clinical follow-up of the newborn who has screened positive; American College of Medical Genetics.

Confirmatory Algorithm for Malonic Aciduria (Elevated C3-DC) (ACMG) (PDF Document 53 KB)
Resource for clinicians to help confirm diagnosis; American College of Medical Genetics.

Services for Patients & Families Nationwide (NW)

Genetics clinic services throughout the US can be found through the Genetics Clinic Services Search Engine (ACMG).

For services not listed above, browse our Services categories or search our database.

* number of provider listings may vary by how states categorize services, whether providers are listed by organization or individual, how services are organized in the state, and other factors; Nationwide (NW) providers are generally limited to web-based services, provider locator services, and organizations that serve children from across the nation.


Malonic Aciduria (
Studies looking at better understanding, diagnosing, and treating this condition; from the National Library of Medicine.

Helpful Articles

PubMed search for malonic aciduria in children

Footitt EJ, Stafford J, Dixon M, Burch M, Jakobs C, Salomons GS, Cleary MA.
Use of a long-chain triglyceride-restricted/medium-chain triglyceride-supplemented diet in a case of malonyl-CoA decarboxylase deficiency with cardiomyopathy.
J Inherit Metab Dis. 2010. PubMed abstract

Authors & Reviewers

Initial publication: March 2007; last update/revision: July 2017
Current Authors and Reviewers:
Author: Nicola Longo, MD, Ph.D.
Authoring history
2011: first version: Nicola Longo, MD, Ph.D.A
AAuthor; CAContributing Author; SASenior Author; RReviewer

Page Bibliography

Genetics Home Reference.
Malonyl-CoA decarboxylase deficiency.
U.S. Library of Medicine; (2017) Accessed on June 2017.

Wightman PJ, Santer R, Ribes A, Dougherty F, McGill N, Thorburn DR, FitzPatrick DR.
MLYCD mutation analysis: evidence for protein mistargeting as a cause of MLYCD deficiency.
Hum Mutat. 2003;22(4):288-300. PubMed abstract