Malonic Acidemia

Guidance for primary care clinicians receiving a positive newborn screen result

Other Names

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

ICD-10 Coding

E71.39, Other disorders of fatty-acid metabolism

Disorder Category

Organic acidemia


Abnormal Finding

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]

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


Fewer than 30 cases have been reported.


Autosomal recessive

Primary Care Management

Next Steps After a Positive Screen

  • Contact the family and evaluate the infant for vomiting, poor feeding, lethargy, and ketonuria.
  • Provide emergency treatment/referral for evidence of hypoglycemia, acidosis, or seizures.

Confirming the Diagnosis

If the Diagnosis is Confirmed

  • For evaluation and ongoing collaborative management, consult Medical Genetics (see UT providers [7]).
  • Provide initial consultation and ongoing collaboration, particularly for dietary management. See Nutrition, Metabolic (see UT providers [11]).
  • Refer the family to Genetic Testing and Counseling (see UT providers [9]).
  • CBS enzyme replacement therapy is currently in the preclinical phase, but clinical trials may be available.
  • 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.


Information & Support

After a Diagnosis or Problem is Identified
Families can face a big change when their baby tests positive for a newborn condition. Find information about A New Diagnosis - You Are Not Alone; Caring for Children with Special Health Care Needs; Assistance in Choosing Providers; Partnering with Healthcare Providers; Top Ten Things to Do After a Diagnosis.

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 Acidemia (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.


UT ACT Sheet for Malonic Acidemia (ACMG) (PDF Document 116 KB)
Contains short-term recommendations for clinical follow-up of the newborn who has screened positive, along with resources for consultation and patient education/support; from the American College of Genetics and Genomics

Confirmatory Algorithm for Malonic Aciduria (Elevated C3-DC) (ACMG) (PDF Document 155 KB)
Resource for clinicians to help confirm diagnosis; American College of Medical Genetics.

Services for Patients & Families in Utah (UT)

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

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