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Screening & Prevention >> Newborn Screening >> Organic Acidemias >> Propionic acidemia

Propionic acidemia

Disorder Category

an organic acid disorder

Screening

Finding

elevated C3 (propionyl carnitine)

Tested By

tandem mass spectrometry (MS/MS); sensitivity: NA; specificity: NA

Names

Propionic acidemia

PA

Propionyl-CoA carboxylase deficiency

Ketotic glycinemia

Ketotic hyperglycinemia

ICD-9

270.7, Other disturbances of straight-chain amino-acid metabolism

Overview

Propionic acidemia (PA) is caused by a defect in a mitochondrial enzyme, propionyl-CoA carboxylase, which is responsible for converting propionyl-CoA to methylmalonyl-CoA and involved in the catabolism of isoleucine, valine, methionine, and threonine. The defect results in the accumulation of precursors, their metabolites, and a deficiency of the products of this catabolism. PA can result in a defect in either of two genes (PCCA and PCCB) that code for the alpha and beta subunits of the enzyme.

Prevalence

About 1/35,000 - 1/75,000 live births; incidence in the Saudi Arabian population is 1/2,000-1/5,000. [Propionic acidemia info for professionals, STAR-G]

Inheritance

autosomal recessive

Prenatal Testing

DNA testing or enzyme analysis by amniocentesis or CVS.

Other Testing

If the familial mutation is known, DNA testing is possible.

Clinical Characteristics

With treatment, normal development and IQ are possible, and symptomatic improvement may be seen in individuals already affected. Without treatment, metabolic crises may lead to progressive neurologic injury and sudden death. Symptoms generally begin within the first few days after birth, though in variant forms they may not begin until after 6 weeks of age. Symptoms may be triggered by fasting and illness and children may be healthy between metabolic crisis episodes. The typical facies of infants with PA includes: frontal bossing, widened depressed nasal bridge, epicanthal folds, long philtrum, upturned curvature of the lips.

Initial signs/symptoms may include:
  • poor feeding;
  • vomiting;
  • seizures;
  • lethargy progressing to coma;
  • lab findings:
    • hypoglycemia;
    • metabolic acidosis;
    • hyperammonemia;
    • ketonuria;
    • neutropenia and thrombocytopenia; and
    • elevated glycine and some organic acid levels in the blood and urine.


If not treated promptly, recurrent metabolic crises may lead to:
  • mental retardation,
  • movement disorders,
  • dystonia,
  • spasticity,
  • stroke,
  • brain damage, and
  • death.


Even with appropriate management, there remains an increased risk of infection and a greater incidence of potentially fatal pancreatitis.

Follow-up on positive screening test

Quantitative plasma acylcarnitine profile, blood amino acid test, urine organic acids, plasma total homocysteine, serum vitamin B12 may reveal PA or variants.

Primary care management

Upon notification of the + screen

  • Contact the family and evaluate the infant for poor feeding, lethargy, vomiting, tachypnea;
  • Provide emergency treatment/referral for symptoms of respiratory distress, metabolic acidosis, hypoglycemia, or seizures;
  • Discontinue breast or cow milk formula feeding;
  • To confirm the diagnosis, work with the following service(s): Utah Newborn Screening Program, (801-584-8256); See also Services below;
  • For evaluation and ongoing collaborative management, consult the following service(s): Metabolic Clinic, (801-585-2457); See also Services below;

If the diagnosis is confirmed

  • Educate the family regarding signs, symptoms, and the need for urgent care when the infant becomes ill (see Propionic acidemia info for parents, STAR-G for additional information);
  • Frequent low protein, low leucine, low valine, low methionine, low threonine, and high carbohydrate meals may be indicated for affected children (this will usually involve medical formulas and foods);
  • Avoidance of fasting; see the child promptly when illness causes poor p.o. intake;
  • Oral L-carnitine, antibiotics, and biotin may be indicated for some children;
  • Bicarbonate and glucose may be indicated during metabolic crisis episodes;
  • Monitoring of amino acid levels through blood and urine tests and monitoring of ketones through urine tests may be indicated;
  • For those identified after irreversible consequences, assist in management, particularly with developmental and educational interventions.

Specialty Care Management

Initial consultation and ongoing collaboration for dietary management, monitoring, and assuring implementation of up-to-date management. Genetic counseling for the family.

Resources

Links

For Professionals

Propionic acidemia info for professionals, STAR-G
On the Screening, Technology and Research in Genetics (STAR-G) site, one of a series of Disorder Fact Sheets for Professionals; structured list of information about the condition, with links to more information.

ACT Sheet for Propionic acidemia from ACMG (pdf 76kb)
Developed by the American College of Medical Genetics (ACMG), includes recommended responses to positive newborn screening test results, diagnostic evaluation, clinical expectations, and sources of additional information. See the ACMG ACT Sheets and Confirmatory Algorithms (link elsewhere on this page) for more info and sheets on other conditions.

ACMG ACT Sheets and Confirmatory Algorithms
The American College of Medical Genetics (ACMG) has developed ACTion (ACT) Sheets and algorithms for responding to positive newborn screening test results. This page contains a table with links to all of the ACT Sheets and related algorithms.

Propionic acidemia, OMIM
From the Online Mendelian Inheritance in Man site, hosted by Johns Hopkins University, providing technical information for providers on genetic disorders, links to MEDLINE, and links to other scientific information and sites.

Propionic acidemia Emergency Protocol
A protocol for management of the patient with a positive screen for propionic acidemia, from the New England Consortium of Metabolic Programs.

For Parents

Propionic acidemia info for parents, STAR-G
From the Screening, Technology and Research in Genetics (STAR-G) site, providing information for parents about propionic acidemia and links to other sites including parent support groups.

Propionic acidemia, Genetics Home Reference
Excellent, detailed review aimed at patients and families from the National Library of Medicine's Genetics Home Reference site.

Propionic Acidemia Foundation
Family support organization site offering information, family stories, frequently asked questions, and other resources.

Organic Acidemia Association (OAA)
A non-profit organization that provides information for parents and providers; newsletters; event information; connections with other parents; a listserv; a discussion board; information about nutrition and recipes; translation of their web pages into five other languages; hosting of the Propionic Acidemia Research Network and other research funds; and links to other sites.

Services

Newborn Screening Programs

Utah Newborn Screening Program, more info...
44 Mario Capecchi Drive
Salt Lake City, UT84114
Phone: 801-584-8256
Fax: 801-536-0966
http://health.utah.gov/newbornscreening

Pediatric Genetics

Metabolic Clinic, more info...
100 Mario Capecchi Drive
Salt Lake City, UT84113
Phone: 801-585-2457
Fax: 585-7252
http://www.ped.med.utah.edu/divisions/divisions.htm

See all Pediatric Genetics services providers (3) in our database.

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

Helpful Articles

PubMed search for articles on propionic acidemia in the last 5 years.

Authors

Reviewing Author: Nicola Longo MD, PhD, 3/2007
Compiled and edited by: Alfred Romeo RN, PhD, 3/2007
Content Last Updated: 3/2008
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