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Screening & Prevention >> Newborn Screening >> Organic Acidemias >> HMG-CoA lyase deficiency

HMG-CoA lyase deficiency

Disorder Category

an organic acid disorder

Screening

Finding

elevated C5-OH (acylcarnitine)

Tested By

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

Names

HMG-CoA lyase deficiency

3-hydroxy-3-methylglutaryl-CoA lyase deficiency

HMG lyase deficiency

Hydroxymethylglutaric aciduria

HL deficiency

ICD-9

270.9, Disorder of amino-acid metabolism

Overview

Lack of the enzyme (usually present in liver, fibroblasts, and leukocytes) impairs the formation of ketone bodies from fat and the break down of leucine resulting in hypoglycemia and accumulation of leucine and other toxic metabolites.

Prevalence

rare [HMG-CoA lyase deficiency info for professionals, STAR-G]

Inheritance

autosomal recessive

Prenatal Testing

DNA testing by amniocentesis or CVS; enzyme testing by urine analysis.

Clinical Characteristics

With treatment, normal development and IQ are possible. However, severe episodes of hypoglycemia may still result in seizures and/or mental retardation. Without treatement, recurring metabolic crises, associated with illness or fasting, will likely result in developmental delay/mental retardation or death. Symptoms generally begin after three months and before two years of age. Affected children may be healthy between metabolic crises.

Initial signs/symptoms may include:
  • poor feeding,
  • vomiting,
  • irritability,
  • lethargy,
  • lab findings:
    • metabolic acidosis, and
    • non-ketotic hypoglycemia.


If not treated promptly and consistently, patients may experience:
  • failure to thrive,
  • hepatomegaly,
  • seizures,
  • apnea,
  • developmental delay/mental retardation, and
  • death.

Follow-up on positive screening test

Quantitative plasma acylcarnitine profile and urine organic acids.

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 (see HMG-CoA lyase deficiency info for parents, STAR-G for additional information);
  • Frequent, low protein, low fat, and high carbohydrate meals - avoidance of fasting;
  • Oral L-carnitine and cornstarch supplementation;
  • Bicarbonate and glucose during metabolic crisis episodes;
  • For those identified after irreversible consequences, assist in management, particularly with developmental and educational interventions.

Specialty Care Management

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

Resources

Links

For Professionals

HMG-CoA lyase deficiency 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 HMG-CoA lyase deficiency from ACMG
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.

HMG-CoA lyase deficiency Emergency Protocol
A protocol for management of the patient with a positive screen for HMG Lyase Deficiency, from the New England Consortium of Metabolic Programs.

HMG-CoA lyase deficiency, OMIM
Extensive review of the literature, including clinical features and gene therapy, 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.

Organic Acidemias, GeneReviews
Excellent and extensive review by Margretta Seashore, MD on the GeneTests.org site; includes causes, evaluation strategy, genetic counseling, management, resources, and references.

For Parents

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

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.

HMG-CoA lyase deficiency, Genetics Home Reference
Excellent, detailed review aimed at patients and families from the National Library of Medicine's Genetics Home Reference site.

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 on HMG-CoA lyase deficiency and newborn infant 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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