Malonic Acidemia

Other Names


Malonyl-CoA decarboxylase deficiency

Malonyl-coenzyme A decarboxylase deficiency



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 can cause cardomyopathy. Treatment involves carnitine supplementation, low-fat diet supplemented with medium chain triglycerides (whose oxidation is not inhibited by malonic acid), and avoidance of fasting. [Wightman: 2003]


Rare - fewer than 20 cases have been reported. [Malonic Aciduria (Genetics Home Reference)]


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

  • Contact the family and evaluate the infant for vomiting, poor feeding, lethargy, ketonuria.
  • Provide emergency treatment/referral for evidence of hypoglycemia, acidosis, seizures.
  • To confirm the diagnosis, work with the following service(s): we currently have no Newborn Screening Programs service providers listed, please search our Services database for related services.
  • For evaluation and ongoing collaborative management, consult the following service(s): we currently have no Pediatric Genetics service providers listed, please search our Services database for related services.

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.
  • Prompt treatment of infections/fever/gastroenteritis with IV fluids containing glucose and hospital admission.
  • For those identified after irreversible consequences, assist in management, particularly with developmental and educational interventions.

Specialty Care Collaboration

Initial consultation and ongoing collaboration, particularly for dietary management. Genetic counseling for the family.


Information & Support

For Professionals

Malonic Aciduria (OMIM)
Extensive review of literature that provides technical information on genetic disorders; Online Mendelian Inheritance in Man site, hosted by Johns Hopkins University.

Malonic Aciduria Fact Sheet (Iowa Dept. of Health) (PDF Document 20 KB)
Provides information for parents and professionals.

Genetics in Primary Care Institute (AAP)
The goal of this site is to increase collaboration in the care of children with known or suspected genetic disorders. It includes health supervision guidelines and other useful resources; represents a collaboration among the Health Resources & Services Administration, the Maternal and Child Health Bureau, and the American Academy of Pediatrics.

For Parents and Patients

Malonic Aciduria (Genetics Home Reference)
Excellent, detailed review of condition for patients and families; sponsored by the U.S. National Library of Medicine.

Baby's First Test: Malonic Aciduria (HHS)
Information about early signs, follow-up testing, treatment, causes, accessing care, and expected outcomes. Provides links to support services; supported by the U.S. Department of Health and Human Services.

Organic Acid Oxidation Disorders - Information for Parents (STAR-G)
A fact sheet, written by a genetic counselor and reviewed by metabolic and genetic specialists, for families who have received an initial diagnosis of a newborn disorder; Screening, Technology and Research in Genetics.

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

National Newborn Screening and Global Resource Center (NNSGRC)
Provides information about each state's newborn screening programs; sponsored by the University of Texas Health Science Center at San Antonio, Department of Pediatrics.


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.


Genetics-related clinical services throughout the world can be found through Genetics Clinic Directory (GeneTests).

Newborn Screening Programs

We currently have no Newborn Screening Programs service providers listed; search our Services database for related services.

Pediatric Genetics

We currently have no Pediatric Genetics service providers listed; search our Services database for related services.

For other services related to this condition, browse our Services categories or search our database.

Helpful Articles

PubMed search for malonic aciduria and neonatal screening, last 5 years.

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
Malonic aciduria, is a rare inborn error of metabolism characterised by a variable phenotype of developmental delay, seizures, cardiomyopathy and acidosis. This case of malonic aciduria with cardiomyopathy demonstrates improvement in cardiac function attributable to LCT-restricted/MCT-supplemented diet.


Reviewing Author: Nicola Longo, MD, PhD - 3/2011
Content Last Updated: 4/2011

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