Recurrent myoglobinuria as a presenting manifestation of very long chain acyl coenzyme A dehydrogenase deficiency

Nutrition management guideline for very-long chain acyl-CoA dehydrogenase deficiency (VLCAD): An evidence- and consensus-based approach

The nutrition management guideline for very-long chain acyl-CoA dehydrogenase deficiency (VLCAD) is the fourth in a series of web-based guidelines focusing on the diet treatment for inherited metabolic disorders and follows previous publication of guidelines for maple syrup urine disease (2014), phenylketonuria (2016) and propionic acidemia (2019). The purpose of this guideline is to establish harmonization in the treatment and monitoring of individuals with VLCAD of all ages in order to improve clinical outcomes. Six research questions were identified to support guideline development on: nutrition recommendations for the healthy individual, illness management, supplementation, monitoring, physical activity and management during pregnancy. This report describes the methodology used in its development including review, critical appraisal and abstraction of peer-reviewed studies and unpublished practice literature; expert input through two Delphi surveys and a nominal group process; and external review from metabolic physicians and dietitians. It includes the summary statements of the nutrition management recommendations for each research question, followed by a standardized rating based on the strength of the evidence. Online, open access of the full published guideline allows utilization by health care providers, researchers and collaborators who advise, advocate and care for individuals with VLCAD and their families and can be accessed from the Genetic Metabolic Dietitians International (https://GMDI.org) and Southeast Regional Genetics Network (https://southeastgenetics.org/ngp) websites.

Recurrent Muscle Weakness with Rhabdomyolysis, Metabolic Crises, and Cardiac Arrhythmia Due to Bi-allelic TANGO2 Mutations

The underlying genetic etiology of rhabdomyolysis remains elusive in a significant fraction of individuals presenting with recurrent metabolic crises and muscle weakness. Using exome sequencing, we identified bi-allelic mutations in TANGO2 encoding transport and Golgi organization 2 homolog (Drosophila) in 12 subjects with episodic rhabdomyolysis, hypoglycemia, hyperammonemia, and susceptibility to life-threatening cardiac tachyarrhythmias. A recurrent homozygous c.460G>A (p.Gly154Arg) mutation was found in four unrelated individuals of Hispanic/Latino origin, and a homozygous ∼34 kb deletion affecting exons 3-9 was observed in two families of European ancestry. One individual of mixed Hispanic/European descent was found to be compound heterozygous for c.460G>A (p.Gly154Arg) and the deletion of exons 3-9. Additionally, a homozygous exons 4-6 deletion was identified in a consanguineous Middle Eastern Arab family. No homozygotes have been reported for these changes in control databases. Fibroblasts derived from a subject with the recurrent c.460G>A (p.Gly154Arg) mutation showed evidence of increased endoplasmic reticulum stress and a reduction in Golgi volume density in comparison to control. Our results show that the c.460G>A (p.Gly154Arg) mutation and the exons 3-9 heterozygous deletion in TANGO2 are recurrent pathogenic alleles present in the Latino/Hispanic and European populations, respectively, causing considerable morbidity in the homozygotes in these populations.

Rhabdomyolysis in a neonate due to very long chain acyl CoA dehydrogenase deficiency

Very long chain acyl CoA dehydrogenase deficiency (VLCADD) is an inborn error in long chain fatty acid oxidation with significant variability in the severity and timing of its clinical presentation. Neonatal presentations of VLCADD have included hypoglycemia and cardiomyopathy while rhabdomyolysis is usually a later onset complication. We describe a neonate with VLCADD presenting with rhabdomyolysis prior to the return of an abnormal newborn screen. This report suggests that evaluating for rhabdomyolysis, in addition to a cardiac and hepatic work-up, is an important part of the initial evaluation of an infant with an abnormal newborn screen suggesting a diagnosis of VLCADD.

Biochemical correction of very long-chain acyl-CoA dehydrogenase deficiency following adeno-associated virus gene therapy

We report the development of a gene replacement strategy for very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency. VLCAD is a mitochondrial enzyme involved in fatty acid beta-oxidation, a key step in energy production during times of fasting or stress. Deficiency of VLCAD classically presents as hepatic dysfunction, hypoglycemia, cardiomyopathy, rhabdomyolysis, and/or sudden death. While dietary therapy for VLCAD deficiency has proven beneficial in preventing some symptoms, a risk of metabolic catastrophic decompensation remains throughout life during times of increased energy demand. We designed a recombinant adeno-associated virus (AAV) expressing the human VLCAD gene (AAV8-hVLCAD). To demonstrate its in vivo activity, AAV8-hVLCAD was administered via the tail vein to VLCAD-knockout mice. A reduction in accumulated serum long-chain acylcarnitines and increased fasting tolerance judged on blood glucose concentrations were observed as of 11 days postinjections through >100 days. Western analysis of liver, skeletal muscle, and heart extracts using PEP1 anti-hVLCAD antibody revealed short-term hVLCAD expression in the liver and muscle and longer-term expression in heart. This demonstrates the ability of human VLCAD to correct the biochemical phenotype of VLCAD-deficient mice.

Fuel utilization in patients with very long-chain acyl-coa dehydrogenase deficiency

Fuel utilization in two adult patients with the myopathic form of very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency and five healthy subjects was investigated with stable isotopes during exercise at 50% of VO2max. The findings indicate that residual VLCAD activity in the patients is sufficient to maintain normal oxidation of fat at rest, but that fat oxidation rate cannot increase above basal levels during exercise. This can cause an energy deficit and intramuscular accumulation of fat intermediates that may induce the exercise-induced symptoms.

Fatal malignant hyperthermia-like syndrome with rhabdomyolysis complicating the presentation of diabetes mellitus in adolescent males

OBJECTIVE

This report describes a new fatal syndrome observed in adolescent males at the initial presentation of diabetes mellitus. The features include hyperglycemic hyperosmolar coma complicated by a malignant hyperthermia-like picture with fever, rhabdomyolysis, and severe cardiovascular instability.

DESIGN

Case series.

SETTING

Pediatric intensive care units of 3 tertiary care facilities in the United States.

PATIENTS

Six adolescent males, 5/6 obese with acanthosis nigricans, 4/6 black.

RESULTS

Four of 6 patients died. Four of 6 patients did not have significant ketosis. Six of 6 patients had increased temperature after the administration of insulin.

CONCLUSIONS

The underlying etiology of this syndrome remains unclear. Possibilities include an underlying metabolic disorder such as a fatty acid oxidation defect, an unrecognized infection, exposure to an unknown toxin, or a genetic predisposition to malignant hyperthermia. Evaluation for all these possibilities and empiric treatment with dantrolene should be considered for this type of patient until this syndrome is better characterized.

A novel mutation of late-onset very-long-chain acyl-CoA dehydrogenase deficiency

We describe a novel mutation in three patients with the myopathic form of very-long-chain acyl-CoA dehydrogenase deficiency. Three siblings born to second-degree cousins of Jewish-Iraqi origin exhibited rhabdomyolysis and myoglobinuria as the presenting signs of the mild late-onset form of very-long-chain acyl-CoA dehydrogenase deficiency. We screened the patients for mutations in the very-long-chain acyl-CoA dehydrogenase gene by amplification of all 20 exons and analysis by single-stranded conformation variance on gel electrophoresis. The patients were homozygous for a novel mutation G637A that alters alanine 173 to threonine. We hypothesize that this missense substitution caused a mild change of enzyme function correlating with the mild clinical features and, thus, favoring a genotype-phenotype correlation.

Myopathic form of very-long chain acyl-coa dehydrogenase deficiency: evidence for temperature-sensitive mild mutations in both mutant alleles in a Japanese girl

In a 14-year-old Japanese girl, manifested recurrent myalgia with elevated serum creatine kinase after moderate exercise became evident, and she was diagnosed as having a myopathic form of very-long chain acyl-CoA dehydrogenase deficiency. Her first clinical symptom of the disease was evident when she was 6 y of age. She had never had hypoglycemic attacks, and hepatomegaly and cardiomyopathy were absent. The diagnosis was suspected on the basis of the urinary organic acid profile after a 36-h fast, long-chain fatty acid-loading test, and the blood acylcarnitine profile. Acyl-CoA dehydrogenase activity with palmitoyl-CoA as a substrate was severely decreased in her fibroblasts, and the amount of very-long chain acyl-CoA dehydrogenase protein was reduced. She was a compound heterozygote of A416T from her father and R450H from her mother. Transient expression of mutant A416T cDNA retained a significant residual acyl-CoA dehydrogenase activity of 10% and 20% normal at 37 degrees C and 30 degrees C, respectively. Specific activity of A416T mutant protein was calculated to be one fifth that of control. In the case of R450H mutant expression, a low residual acyl-CoA dehydrogenase activity of 5% normal was detected at 30 degrees C although significant activity was absent at 37 degrees C. The R450H protein was not detected at 37 degrees C but was clearly detected at one fourth the normal amount at 30 degrees C. These results indicate that both mutations were temperature-sensitive mild mutations, the result being the mildest phenotype of very-long chain acyl-CoA dehydrogenase deficiency.

Hypoglycemia in association with various organic and amino acid disorders

A number of organic and amino acidemias, particularly those that involve the oxidation of fatty acids, cause hypoglycemia intermittently. This may be associated with distrubances of acid base equilibrium and accumulation of lactic acid and/or ketone bodies. When such diseases are not diagnosed rapidly, they might lead to neurological crippling and, at times, death. As a group, these disorders involve more than 1 organ and their phenotypic expression may include all or a single system. The symptoms may appear soon after birth or as late as 1 year of age. Their early recognition and rapid intervention provide rewarding clinical outcome. With the recent advances in diagnostic techniques, such as the introduction of tandem mass spectrometry (MS), screening for these diseases now can be performed because rapid identification on a large scale is possible. The phenotypes, mutations involved, pathognomonic laboratory findings, prognosis, and treatment procedures available have been reviewed for major diseases.

Clinical and molecular heterogeneity in very-long-chain acyl-coenzyme A dehydrogenase deficiency

Very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency is an increasingly recognized defect of mitochondrial fatty acid beta-oxidation manifesting with episodes of metabolic decompensation or isolated recurrent myoglobinuria. In this report the clinical, biochemical, and molecular studies in a series of five patients (four Italian and one Spanish) with this disorder are discussed. Biochemical studies included the determination of fibroblast substrate oxidation rates and enzyme activity and Western blot analysis of VLCAD protein. Molecular analysis was performed by sequencing the VLCAD gene from the genomic DNA. Clinical features were within the spectrum previously reported. Four patients presented in infancy or childhood with episodes of severe metabolic decompensation and dicarboxylic aciduria. Two exhibited cardiomyopathy. The fifth patient presented with isolated recurrent rhabdomyolysis, with no cardiomyopathy or dicarboxylic aciduria. In all patients a significant loss of VLCAD activity associated with a marked reduction of VLCAD protein levels occurred. Molecular analysis disclosed one novel missense mutation (Cys437Tyr) and four previously reported mutations, including two missense substitutions (Phe418Leu and Arg419Trp), a single amino acid deletion (Lys258del), and one splice site mutation (IVS8-C(-2)), which was present in all four Italian patients. All patients exhibited compound heterozygosity. The phenotypic variability and the high genotypic heterogeneity of this hereditary metabolic disorder is reported.

Adolescent myopathic presentation in two sisters with very long-chain acyl-CoA dehydrogenase deficiency

Two sisters were investigated at the ages of 20 and 13 years owing to persistently increased serum creatine kinase and recurrent episodes of rhabdomyolysis after emotional stress in the older and myalgias in the younger. The finding of increased levels of cis-5-tetradecenoic acid (C14:1) in plasma, severe hypocarnitinaemia and the absence of a pathological dicarboxylic aciduria in both sisters suggested a very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency. Reduced [1-(14)C]palmitate oxidation and deficient mitochondrial VLCAD activity in fibroblasts were found. Mutation analysis revealed compound heterozygosity for Asp365His and Arg410His changes. This late-onset, milder clinical presentation differs from the other two more severe infantile phenotypes described, since there is no hypoglycaemia or cardiac disease. Fatty acid oxidation defects should be investigated in all cases with rhabdomyolysis beginning in adolescence or early adulthood.

Very long chain acyl coenzyme A dehydrogenase deficiency in a 5-month-old Korean boy: identification of a novel mutation

A 5-month-old Korean boy who presented with lethargy and cardiomyopathy was diagnosed with very long chain acyl coenzyme A dehydrogenase (VLCAD) deficiency by organic acid, fatty acid, acylcarnitine, and molecular genetic analysis. The patient was a compound heterozygote for mutations in the VLCAD gene. One allele contains a 3-bp deletion in exon 6, deleting glutamic acid in codon 130 (E130del ); this allele is of paternal origin. The patient's maternally derived allele is a novel mutation, C1843T in exon 20, which creates a premature termination codon (R615stop ). Although molecular genetic characterization of VLCAD deficiency is limited to a few patients, heterogeneity of mutations is already apparent. However, the E130del is a relatively frequent mutant allele, which has been noted in 2 previously identified patients. The 2 mutant alleles in our patient appear to be responsible for his severe and fatal clinical manifestations.

Myopathy in very-long-chain acyl-CoA dehydrogenase deficiency: clinical and biochemical differences with the fatal cardiac phenotype

A 30-year-old man suffered since the age of 13 years from exercise induced episodes of intense generalised muscle pain, weakness and myoglobinuria. Fasting ketogenesis was low, while blood glucose remained normal. Muscle mitochondria failed to oxidise palmitoylcarnitine. Palmitoyl-CoA dehydrogenase was deficient in muscle and fibroblasts, consistent with deficiency of very-long-chain acyl-CoA dehydrogenase (VLCAD). The gene of this enzyme had a homozygous deletion of three base pairs in exon 9, skipping lysine residue 238. Fibroblasts oxidised myristate, palmitate and oleate at a rate of 129, 62 and 38% of controls. In contrast to patients with cardiac VLCAD deficiency, our patient had no lipid storage, a normal heart function, a higher rate of oleate oxidation in fibroblasts and normal free carnitine in plasma and fibroblasts. 31P-nuclear magnetic resonance spectroscopy of muscle showed a normal oxidative phosphorylation as assessed by phosphocreatine recovery, but a significant increase in pH and in Pi/ATP ratio.

Clear correlation of genotype with disease phenotype in very-long-chain acyl-CoA dehydrogenase deficiency

Very-long-chain acyl-CoA dehydrogenase (VLCAD) catalyzes the initial rate-limiting step in mitochondrial fatty acid beta-oxidation. VLCAD deficiency is clinically heterogenous, with three major phenotypes: a severe childhood form, with early onset, high mortality, and high incidence of cardiomyopathy; a milder childhood form, with later onset, usually with hypoketotic hypoglycemia as the main presenting feature, low mortality, and rare cardiomyopathy; and an adult form, with isolated skeletal muscle involvement, rhabdomyolysis, and myoglobinuria, usually triggered by exercise or fasting. To examine whether these different phenotypes are due to differences in the VLCAD genotype, we investigated 58 different mutations in 55 unrelated patients representing all known clinical phenotypes and correlated the mutation type with the clinical phenotype. Our results show a clear relationship between the nature of the mutation and the severity of disease. Patients with the severe childhood phenotype have mutations that result in no residual enzyme activity, whereas patients with the milder childhood and adult phenotypes have mutations that may result in residual enzyme activity. This clear genotype-phenotype relationship is in sharp contrast to what has been observed in medium-chain acyl-CoA dehydrogenase deficiency, in which no correlation between genotype and phenotype can be established.

Fatty acid oxidation defects in muscle

Fatty acid oxidation defects can cause recurrent rhabdomyolysis or chronic progressive muscle weakness. Diagnosis is often possible on blood using tandem mass spectrometry or molecular genetic techniques. Riboflavin and carnitine are effective in some cases of multiple acyl-CoA dehydrogenase deficiency and primary carnitine deficiency, respectively. Controlled trials are needed to evaluate other proposed forms of treatment.

Very-long-chain acyl-coenzyme A dehydrogenase deficiency in a child with recurrent myoglobinuria

A 9-year-old boy had recurrent episodes of myoglobinuria and normal urinary organic acid profile. Very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency was detected biochemically in cultured skin fibroblasts and confirmed by Western blot analysis. The patient had a distinctive plasma fatty-acid profile, which was present even between attacks. Early diagnosis of this disorder is important because of the apparently protective effect of an appropriate dietary regimen.