Medium-Chain Acyl-CoA Dehydrogenase Deficiency (MCADD)

Guidance for primary care clinicians receiving a positive newborn screen result

Other Names

ACADM deficiency
MCADD

ICD-10 Coding

E71.311, Medium-chain acyl-CoA dehydrogenase deficiency

Disorder Category

Fatty acid oxidation disorder

Screening

Abnormal Finding

Elevated C8 (octanoylcarnitine) with lesser elevations of C6 (hexanoylglycine) and C10:1 (decenoyl carnitine)

Tested By

Tandem mass spectrometry (MS/MS); sensitivity=100%; specificity=99.98% [Schulze: 2003]

Description

Medium-chain acyl-CoA dehydrogenase is one of several enzymes involved in the beta-oxidation of fatty acids within mitochondria for energy production. Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) impairs hepatic ketogenesis, resulting in hypoketotic hypoglycemia during prolonged fasting or increased energy demands (e.g., acute illness or fever).

Clinical Characteristics

With treatment of MCADD, the prognosis is excellent. Even during periods of metabolic stress, long-term complications can be avoided by providing nutrition via other means including dextrose-containing intravenous fluids if not able to tolerate enteral feeds.

Without treatment, patients initially appear very well until an episode is triggered, typically presenting as hypoketotic hypoglycemic with lethargy and vomiting that may progress to seizures, coma, cardiac arrest, and sudden death. Before newborn screening, most would experience their first episode before 2 years of age, though late-onset adult presentations have been reported. [Lang: 2009] Typical triggers include anything that would cause increased metabolic demands, such as prolonged fasting, vomiting/dehydration, infections, fever, and alcohol intoxication. Historically, 18-25% of affected individuals would die during their initial metabolic crisis if the diagnosis had not previously been established. Despite recovery, recurrent uncontrolled metabolic decompensations can also cause sustained brain injury resulting in loss of developmental milestones and muscle weakness.
Initial symptoms/signs of MCADD may include:
  • Poor feeding
  • Vomiting
  • Lethargy progressing to coma
  • Lab findings:
    • Hypoketotic hypoglycemia
    • Increased anion gap
    • Hyperammonemia
    • Elevated ALT and AST
Subsequent symptoms/signs may include:
  • Hepatomegaly
  • Liver dysfunction
  • Seizures
  • Encephalopathy
  • Sudden death

Incidence

The incidence of MCADD ranges from 1:13,000 to 1:19,000 live births across the United States, with similar rates in most parts of Europe, Australia, Canada, and Saudi Arabia. [Therrell: 2014] [Wilcken: 2009] [Kasper: 2010] [Prasad: 2012]

Inheritance

Autosomal recessive

Primary Care Management

Next Steps After a Positive Screen

  • Contact the family immediately and evaluate the infant for related symptoms.
  • Provide emergency treatment and referral for symptoms of hypoglycemia, lethargy, and feeding problems.
  • Ensure the child eats at regular intervals (every 3 to 4 hours), and formula is available to the family if breastfeeding becomes insufficient.

Confirming the Diagnosis

  • To confirm the diagnosis of MCADD, work with Newborn Screening Services (see NM providers [1]).
  • Follow-up testing may include quantitative plasma acylcarnitine profile, urine acylglycine (increased hexanoylglycine), urine organic acids, and DNA analysis.

If the Diagnosis is Confirmed

  • Evaluate and continue ongoing collaborative management, consult Biochemical Genetics (Metabolics) Clinics (see NM providers [1]).
  • Educate the family about signs, symptoms, the need for frequent feedings, and the need for urgent care if the infant becomes ill. See MCADD - Information for Parents (STAR-G) for additional information.
  • Provide an "emergency" letter guiding caregivers in the appropriate response to acute illness and a medical ID bracelet for older kids and adults.
  • Consider a heart-healthy diet for affected children after 1 year of age.
  • Consider oral L-carnitine, which may be recommended in case of deficiency.
  • Assist in the management of irreversible consequences as necessary, particularly with developmental and educational interventions.

Resources

Information & Support

Related Portal Content
MCADD
Assessment and management information for the primary care clinician caring for the child with medium-chain acyl-CoA dehydrogenase deficiency.

Fatty Acid Oxidation Disorders (MCADD, LCHADD, VLCADD) (FAQ)
Answers to questions families often have about caring for their child with MCADD.

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; 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

Medium-Chain Acyl-Coenzyme A Dehydrogenase Deficiency (GeneReviews)
Excellent review of MCADD that includes a clinical description, differential diagnoses, management information, and molecular genetic information; sponsored by the U.S. National Library of Medicine.

For Parents and Patients

MCADD - 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 this newborn disorder; Screening, Technology and Research in Genetics.

Medium-chain acyl-CoA dehydrogenase deficiency (MedlinePlus)
Information for families that includes description, frequency, causes, inheritance, other names, and additional resources; from the National Library of Medicine.

Fatty Oxidation Disorders (FOD) Family Support Group
Information for families about fatty acid oxidation disorders, support groups, coping, finances, and links to other sites.

Tools

Confirmatory Algorithm for MCAD Deficiency (PDF Document 170 KB)
Resource for clinicians to help confirm diagnosis; American College of Medical Genetics.

Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCADD) (NECMP) (PDF Document 17 KB)
Guideline for clinicians treating the sick infant or child who has MCADD; developed under the direction of Dr. Harvey Levy, Senior Associate in Medicine/Genetics at Children’s Hospital Boston, and Professor of Pediatrics at Harvard Medical School, for the New England Consortium of Metabolic Programs. Click pdf to view the complete protocol.

NM ACT Sheet for MCADD (C8-C6-C10) (ACMG) (PDF Document 139 KB)
Provides recommendations for clinical and laboratory follow-up of the newborn with out-of-range screening results, along with national and local resources for clinicians and families; American College of Medical Genetics.

Services for Patients & Families in New Mexico (NM)

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.

Helpful Articles

PubMed search for MCADD in children, last 4 years.

Leonard JV, Dezateux C.
Newborn screening for medium chain acyl CoA dehydrogenase deficiency.
Arch Dis Child. 2009;94(3):235-8. PubMed abstract

Authors & Reviewers

Initial publication: March 2007; last update/revision: April 2022
Current Authors and Reviewers:
Author: Brian J. Shayota, MD, MPH
Authoring history
2015: first version: Nicola Longo, MD, Ph.D.A
AAuthor; CAContributing Author; SASenior Author; RReviewer

Page Bibliography

Kasper DC, Ratschmann R, Metz TF, Mechtler TP, Möslinger D, Konstantopoulou V, Item CB, Pollak A, Herkner KR.
The national Austrian newborn screening program - eight years experience with mass spectrometry. past, present, and future goals.
Wien Klin Wochenschr. 2010;122(21-22):607-13. PubMed abstract

Lang TF.
Adult presentations of medium-chain acyl-CoA dehydrogenase deficiency (MCADD).
J Inherit Metab Dis. 2009;32(6):675-83. PubMed abstract

Prasad C, Speechley KN, Dyack S, Rupar CA, Chakraborty P, Kronick JB.
Incidence of medium-chain acyl-CoA dehydrogenase deficiency in Canada using the Canadian Paediatric Surveillance Program: Role of newborn screening.
Paediatr Child Health. 2012;17(4):185-9. PubMed abstract / Full Text

Schulze A, Lindner M, Kohlmuller D, Olgemoller K, Mayatepek E, Hoffmann GF.
Expanded newborn screening for inborn errors of metabolism by electrospray ionization-tandem mass spectrometry: results, outcome, and implications.
Pediatrics. 2003;111(6 Pt 1):1399-406. PubMed abstract

Therrell BL Jr, Lloyd-Puryear MA, Camp KM, Mann MY.
Inborn errors of metabolism identified via newborn screening: Ten-year incidence data and costs of nutritional interventions for research agenda planning.
Mol Genet Metab. 2014;113(1-2):14-26. PubMed abstract / Full Text

Wilcken B, Haas M, Joy P, Wiley V, Bowling F, Carpenter K, Christodoulou J, Cowley D, Ellaway C, Fletcher J, Kirk EP, Lewis B, McGill J, Peters H, Pitt J, Ranieri E, Yaplito-Lee J, Boneh A.
Expanded newborn screening: outcome in screened and unscreened patients at age 6 years.
Pediatrics. 2009;124(2):e241-8. PubMed abstract