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eMedicine Journal > Pediatrics > Genetics And Metabolic Disease
Long-Chain Acyl CoA Dehydrogenase Deficiency

Synonyms, Key Words, and Related Terms: long-chain acyl CoA dehydrogenase deficiency, LCHAD deficiency, trifunctional protein deficiency
Author Information | Introduction | Clinical | Differentials | Workup | Treatment | Medication | Follow-up | Miscellaneous | Test Questions | Bibliography

AUTHOR INFORMATION Section 1 of 11    Click here to go to the top of this page Click here to go to the next section in this topic

Authored by Fernando Scaglia, MD, Assistant Professor of Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine and Texas Children's Hospital

Fernando Scaglia, MD, is a member of the following medical societies: American Academy of Pediatrics, American Medical Association, American Society of Human Genetics, Juvenile Diabetes Foundation, and Society for Inherited Metabolic Disorders

Edited by Karl S Roth, MD, Chair, Professor, Department of Pediatrics, Creighton University School of Medicine; Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc; Margaret McGovern, MD, PhD, Vice Chair, Professor, Department of Human Genetics, Mount Sinai School of Medicine; Paul D Petry, DO, FACOP, FAAP, Clinical Assistant Professor of Pediatrics, University of North Dakota, School of Medicine and Health Sciences; Consulting Staff, Altru Health System; and Bruce A Buehler, MD, Professor, Department of Pathology and Microbiology, Chairman, Department of Pediatrics, Director, Hattie B Munroe Center for Human Genetics, University of Nebraska Medical Center

Author's Email:Fernando Scaglia, MDClick here to view conflict-of-interest information on the author of this topic
Editor's Email:Karl S Roth, MD 

eMedicine Journal, August 2 2006, VOLUME 7, Number 8
INTRODUCTION Section 2 of 11   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

Background: Long-chain 3-hydroxy acyl-coenzyme A dehydrogenase (LCHAD) is 1 of 3 enzymatic activities that make up the trifunctional protein of the inner mitochondrial membrane. The other 2 activities of the protein are 2-enoyl coenzyme A (CoA) hydratase (LCEH) and long-chain 3-ketoacyl CoA thiolase (LCKT). The protein is an octamer composed of 4 alpha subunits that contain the LCEH and LCHAD activities, and 4 beta subunits that contain the LCKT activity. This enzyme complex metabolizes long-chain fatty acids, and the LCHAD activity is specific for compounds of C12-C16 chain length. The genes for the alpha and beta subunits have been localized to chromosome 2. Affected infants with LCHAD deficiency, which is inherited as an autosomal recessive trait, present in infancy with acute hypoketotic hypoglycemia. These episodes typically appear for the first time after a fast, which usually occurs in the context of intercurrent illness with vomiting.

Pathophysiology: The molecular defect occurs in the mitochondrial trifunctional protein (MTP). Some patients who are deficient in all 3 enzymatic activities of the protein have been described, though most have an isolated LCHAD deficiency, which results in the inability to metabolize long-chain fatty acids. Thus, the clinical features may result from either toxicity due to long-chain acyl-CoA esters that cause cardiomyopathy and cardiac arrhythmias or from a block in long-chain fatty acid oxidation that leads to an inability to synthesize ketone bodies and/or adenosine triphosphate from long-chain fatty acids. The gene for the protein has been cloned and a common mutation, G1528C, has been identified in 87% of mutant alleles.

The fatty acid oxidation defect results in adverse effects on a number of organ systems, including the CNS, secondary to the hypoketotic hypoglycemia. Hypotonia and cardiomyopathy also are usually present, reflecting the underlying energy deficiency. In addition, hepatomegaly usually is evident, and biopsy of the liver reveals fat accumulation and fibrosis.

Frequency:

Mortality/Morbidity: In the majority of cases, the disease is severe and may lead to death during the first few months of life. The disease also may be a cause of sudden infant death, even neonatal. For those infants that are diagnosed and treated, a risk still exists for psychomotor retardation.

Race: Patients from all ethnic groups have been reported.

Sex: No sexual predilection exists because this is an autosomal recessive disorder.

Age: Patients with LCHAD deficiency usually present with hypoketotic hypoglycemia, cardiomyopathy, hypotonia, and hepatomegaly at a median age of 6 months. In childhood, the presentation is myopathic. A minority of patients (up to 15%) may present during the neonatal period. A late-onset neuromuscular disease has been reported in MTP deficiency.
CLINICAL Section 3 of 11   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

History:

Physical:

Causes:

DIFFERENTIALS Section 4 of 11   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

Acidosis, Metabolic
Cardiomyopathy, Dilated
Carnitine Deficiency
Hypoglycemia


Other Problems to be Considered:

Reye syndrome
Other disorders of very long-chain fatty acid oxidation (VLCAD)
Respiratory chain defects (complex I deficiency)

WORKUP Section 5 of 11   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

Lab Studies:

Imaging Studies:

Other Tests:

Procedures:

Histologic Findings: Pathological evaluation has revealed microvesicular and macrovesicular accumulation of fat in skeletal muscle, heart, and liver. Necrotic myopathy without steatosis has been described, as well as degeneration of muscle fibers. Hepatic cirrhosis also has been observed.

Ultrastructurally, the mitochondria appear to be increased in size and number with swollen appearance. Condensation of the mitochondrial matrix and irregular cristae is noted.

TREATMENT Section 6 of 11   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

Medical Care:

Consultations:

Diet:

Activity:

MEDICATION Section 7 of 11   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

Try carnitine supplementation in patients with evident hypocarnitinemia and continue if symptoms improve; however, start carnitine supplementation with caution during acute fulminant symptoms because of the potential risk of cardiac arrhythmias.

Drug Category: Dietary supplements -- L-carnitine at high doses corrects the metabolic abnormalities and hypocarnitinemia present in cases of LCHAD deficiency. It may be important for the conjugation and excretion of fatty acids, for the enhancement of the excretion of toxic metabolites, and to generate free CoA; however, use with extreme caution during acute metabolic crises.
Drug Name
Levocarnitine (Carnitor) -- An amino acid derivative synthesized from methionine and lysine, required in energy metabolism. Can promote excretion of excess fatty acids in patients with defects in fatty acid metabolism or specific organic acidopathies, which bioaccumulate acyl CoA esters. Normal levels occur in liver, and mild level increases occur in skeletal muscle.
High doses are able to restore the level of free carnitine in plasma to normal, and many patients improve with this therapy; however, the concentration of long-chain acyl-carnitines increases, which can be detrimental and cause serious cardiac arrhythmias in fulminant crises.
Use in long-chain fatty acid oxidation disorders (eg, LCHAD deficiency, MTP deficiency) is a matter of continued debate, mainly during acute fulminant crises when it enhances the formation of long-chain acylcarnitines, which may cause ventricular arrhythmogenesis.
Adult Dose1 g/dose PO/IV tid; not to exceed 3 g/d
Pediatric Dose100-200 mg/kg/d PO divided bid/tid; not to exceed 3 g/d
ContraindicationsDocumented hypersensitivity
InteractionsNone known
Pregnancy B - Usually safe but benefits must outweigh the risks.
PrecautionsDo not use in acute metabolic crises; monitor blood chemistries, vital signs, plasma carnitine concentrations and overall clinical condition; in secondary carnitine deficiency, a number of metabolic disorders must be diagnosed correctly before initiation of carnitine supplementation; use in long-chain fatty acid oxidation defects (eg, LCHAD deficiency, trifunctional protein deficiency, VLCAD deficiency) may enhance formation of long-chain acylcarnitines, which may cause ventricular arrhythmogenesis; adverse effects with toxic doses are nausea, vomiting, diarrhea, and a fish odor derived from a metabolite of carnitine (trimethylamine)
FOLLOW-UP Section 8 of 11   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

Further Inpatient Care:

Further Outpatient Care:

In/Out Patient Meds:

Transfer:

Deterrence/Prevention:

Complications:

Prognosis:

Patient Education:

MISCELLANEOUS Section 9 of 11   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

Medical/Legal Pitfalls:

Special Concerns:

TEST QUESTIONS Section 10 of 11   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

CME Question 1: Which of the following features is not a characteristic of long-chain 3-hydroxy acyl-coenzyme A dehydrogenase (LCHAD) deficiency?


A: Pigmentary retinopathy
B: Progressive sensorimotor neuropathy
C: Liver failure
D: Hypoglycemic hypoketotic encephalopathy
E: Renal cysts

The correct answer is E: Renal cysts are found in association with carnitine palmityl transferase II, glutaric aciduria type II, and multiple acyl-coenzyme A (CoA) dehydrogenase deficiency. All of the other features are present or can manifest with LCHAD deficiency.

CME Question 2: Which of these dietary supplements may be used in the treatment of long-chain 3-hydroxy acyl-coenzyme A dehydrogenase (LCHAD) deficiency?


A: Biotin
B: Pantothenic acid
C: Carnitine
D: Coenzyme Q10
E: Uridine

The correct answer is C: Carnitine could be used in the chronic treatment if hypocarnitinemia is documented and if it helps to alleviate symptoms; however, carnitine should be used with care in cases of acute decompensation because it may enhance ventricular arrhythmias.

Pearl Question 1 (T/F): The mean age of onset of long-chain 3-hydroxy acyl-coenzyme A dehydrogenase (LCHAD) deficiency symptoms is 12 months.

The correct answer is True: Patients with LCHAD usually present in late infancy with the hallmark feature of acute hypoketotic hypoglycemia. These episodes often present late in the first year of life, with the first long fast usually caused by an intercurrent infectious illness.

Pearl Question 2 (T/F): Cataracts are a common feature of long-chain 3-hydroxy acyl-coenzyme A dehydrogenase (LCHAD) deficiency.

The correct answer is False: Cataracts are not a common feature of LCHAD deficiency. The initial ophthalmological abnormalities are fundus changes with aggregation of pigment in the macular region.

Pearl Question 3 (T/F): Gestational diabetes is the typical pregnancy complication affecting pregnancies with a long-chain 3-hydroxy acyl-coenzyme A dehydrogenase (LCHAD)-deficient fetus.

The correct answer is False: Gestational diabetes is not the typical pregnancy complication derived from pregnancies with an LCHAD-deficient fetus. The combination of preeclampsia, hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome, and acute fatty liver of pregnancy (AFLP) were detected in 31% of pregnancies in a series of 18 female carriers of LCHAD deficiency.

Pearl Question 4 (T/F): In infancy and early childhood, the main manifestations of long-chain 3-hydroxy acyl-CoA dehydrogenase deficiency are attacks of rhabdomyolysis with muscle pain and weakness.

The correct answer is False: Attacks of rhabdomyolysis are more predominant later in childhood, whereas in infancy and early childhood the main manifestations are periods of hypoketotic hypoglycemia with cardiomyopathy, hypotonia, and hepatomegaly.
BIBLIOGRAPHY Section 11 of 11   Click here to go to the next section in this topic Click here to go to the top of this page

NOTE:
Medicine is a constantly changing science and not all therapies are clearly established. New research changes drug and treatment therapies daily. The authors, editors, and publisher of this journal have used their best efforts to provide information that is up-to-date and accurate and is generally accepted within medical standards at the time of publication. However, as medical science is constantly changing and human error is always possible, the authors, editors, and publisher or any other party involved with the publication of this article do not warrant the information in this article is accurate or complete, nor are they responsible for omissions or errors in the article or for the results of using this information. The reader should confirm the information in this article from other sources prior to use. In particular, all drug doses, indications, and contraindications should be confirmed in the package insert. FULL DISCLAIMER
eMedicine Journal, August 2 2006, VOLUME 7, Number 8
© Copyright 2001, eMedicine.com, Inc.

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