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Myopathic Carnitine Deficiency

Muscle carnitine deficiency

Myopathic carnitine deficiency (MCD) is a type of primary carnitine deficiency. It is a hereditary disorder that differs from systemic carnitine deficiency (SCD) in that low levels of carnitine occur in the muscles only, while plasma concentrations of carnitine are within physiological ranges. Symptoms are non-specific and comprise progressive muscle weakness, increased muscle fatigue, and myalgia. Cardiomyopathy is a rare but life-threatening complication of MCD, which usually follows a benign course. The diagnosis of MCD is based on clinical and histological findings, namely lipid storage in muscle cells. The underlying gene defect could not yet be identified and, in view of the phenotypic heterogeneity, may indeed vary between individual patients.


Presentation

MCD is characterized by progressive muscle weakness due to lipid storage myopathy, primarily in type I muscle fibers [1]. Symptom onset may occur during infancy but is often delayed until the second or third decade of life [2] [3] [4]. Isolated cases have been described of patients seeking medical attention in old age only [5] [6], but regardless of their age at first presentation, the majority of individuals with MCD has a longstanding history of minor, non-disabling muscle weakness [2] [5]. They may describe predominantly proximal myalgia and muscular fatigability most pronounced during prolonged physical exercise [7]. As the disease progresses, symptoms may become present at rest and increasingly interfere with everyday activities.

Hypertrophic cardiomyopathy is not a common feature but has been described repeatedly [8] [9] [10]. It may lead to congestive heart failure and premature death. These patients may present with generalized fatigue and weakness, decreased tolerance to exercise, dyspnea, and cough. They may or may not present any of the classical symptoms of MCD [8].

Asymptomatic
  • Patients are asymptomatic between episodes of rhabdomyolysis. Etiology Several missense mutations in the CPT2 gene result in the myopathic form of CPT II deficiency.[orpha.net]
  • Two other patients with mitochondrial myopathies (one with an unidentified enzyme defect, 8 one with carnitine palmitoyl transferase deficiency 9 ) were asymptomatic during pregnancy and after delivery.[jnnp.bmj.com]
  • Sudden death: Unfortunately, the first clinical manifestation in asymptomatic individuals with primary carnitine deficiency may be sudden death.[emedicine.medscape.com]
  • Some people with primary carnitine deficiency are asymptomatic, which means they do not have any signs or symptoms of the condition. All individuals with this disorder are at risk for heart failure, liver problems, coma, and sudden death.[ghr.nlm.nih.gov]
  • […] or type 2 atrophy Prognosis Weakness resolves 2 to 4 months after thyroid hormone normalization Other features Tremor (76%) Hyperreflexia (38%) Paresthesias & Numbness: With high free T4 Hyperthyroid ophthalmopathy β-adrenergic hyperactivity Mild or asymptomatic[neuromuscular.wustl.edu]
Inflammation
  • Signs of inflammation were not present. Histochemical stains disclosed prominent storage of lipid droplets in the muscle fibres. In addition, single fibres showed slightly reduced activity of cytochrome c oxidase.[jnnp.bmj.com]
  • […] disorders, glutaric aciduria type 1 [11] , hair loss, heart attack [9] , heart failure, high cholesterol or triglycerides, hyperthyroidism, HIV/AIDS, infertility in males, irregular heart beat (arrhythmia), leg ulcers, Lyme disease, migraine, myocarditis (inflammation[nutrientsreview.com]
  • Muscle inflammation, atrophy, necrosis, denervation, or neuromuscular disease can alter these components, giving rise to patterns that may help illuminate the underlying pathology.[aafp.org]
  • […] in orbital myositis Orbital echography Restrictive ophthalmopathy: Forced duction testing Treatment Protection of eye from keratitis Drugs: Prednisone; Cyclosporine; Pentoxifylline Treat thyroid disorder Orbital radiation: for acute disease & active inflammation[neuromuscular.wustl.edu]
  • ) ( 11 ) , we categorized the final diagnosis according to the most prominent histological features, such as (a) consistent with myopathy (random variation in fiber size with small rounded fibers, necrosis, phagocytosis, regenerating muscle fibers, inflammation[academic.oup.com]
Swelling
  • This can lead to symptoms such as swelling and shortness of breath. Untreated heart weakness may lead to death early in life. Fortunately, heart problems respond very well to treatment with L-carnitine.[cedars-sinai.org]
  • Secondary carnitine deficiency in children may present with loss of muscle tone, failure to thrive, recurrent infection, swelling of the brain, hypoglycemia , heart disturbances, and may be fatal.[ndhealthfacts.org]
  • […] change in muscle: Up to 90% Hashimoto's thyroiditis (Autoimmune hypothyroidism): 5% No clinical thyroid dysfunction: 5% Other risk factors for DO Sex: Female Smoking Lithium treatment Radioiodine therapy for hypothyroidism Clinical features Soft tissue swelling[neuromuscular.wustl.edu]
  • The skeletal examination may reveal the leg bowing and pseudofractures of osteomalacia or the symmetric joint swelling of lupus and rheumatoid arthritis. 8 , 17 , 18 , 21 , 25 , 35 Laboratory and Radiologic Evaluation The sequence and timing of the ancillary[aafp.org]
Malnutrition
  • The health problems that can cause this include: Liver disease Kidney disease, especially with dialysis Digestive disease that causes poor absorption Malnutrition Mitochondrial disease Certain metabolic disorders Certain medicines, such as valproate Who[cedars-sinai.org]
  • Angiography with venous sampling for insulin levels (80%) Tumor types: Insulinoma (80%); Islet cell carcinoma (10%); MEN1 syndrome with multiple tumors Gynecomastia & Neuromuscular Bulbospinal muscular atrophy Adrenomyeloneuropathy Recovery from severe malnutrition[neuromuscular.wustl.edu]
Erythema
  • Increased Susceptibility Clinical Skin: Most patients; Usual presenting feature Livido reticularis Thickening Painful necrotic lesions Well demarcated erythema; Bullae; Ecchymoses Proximal Distal (68%) Lower Upper Ischemia of digits Lesions may cause[neuromuscular.wustl.edu]
  • […] endogenously synthesized triglycerides; cells can utilize exogenous phospholipids and triglycerides Clinical features: Congenital ichthyosis Age of onset: second decade in most patients Ichthyosis: Lamellar ichthyosis Accentuated over the flexor creases Mild erythema[neurodiffdx.com]
  • ., skin bronzing in adrenal insufficiency; Gottron’s papules and heliotrope rash in dermatomyositis; and erythema nodosum in sarcoidosis).[aafp.org]
Myalgia
  • […] diaphragm disease Dimauro Disease early infantile epileptic encephalopathy 39 Early-Onset Myopathy with Fatal Cardiomyopathy EHLERS-DANLOS SYNDROME, KYPHOSCOLIOTIC TYPE, 2 ENCEPHALOPATHY DUE TO DEFECTIVE MITOCHONDRIAL AND PEROXISOMAL FISSION 2 eosinophilia-myalgia[rgd.mcw.edu]
  • […] myopathies general •normal muscle function depends on adequante ATP -derived from glycogen, lipid and normal mitochondrial function •Glycogenoses •Carnitine deficiency (lipid metabolism) •Mitochondrial (encephalomyopathies) •exercise-induced weakness, myalgias[quizlet.com]
  • Related to high levels of ACTH produced by pituitary Adrenal insufficiency From Bramwell: Atlas of Clinical Medicine Addison's Disease Clinical Muscle Fatigue Weakness: Mild; Occasionally respiratory Cramps Myalgias Rhabdomyolysis Systemic Weight loss[neuromuscular.wustl.edu]
  • Recurrent exertional myalgia and myoglobinuria due to carnitine palmityltransferase deficiency. Isr J Med Sci. 1983 Jun; 19 (6):552–554. [ PubMed ] [ Google Scholar ] Sugiyama N, Wada Y, Morishita H, Nonaka I.[ncbi.nlm.nih.gov]
  • Patients can clinically present with cardiomyopathy, skeletal muscle weakness, myalgia, and extreme fatigue. An early diagnosis is crucial, as some LSMs can be managed by simple nutraceutical supplementation. For example, high dosage ...[allmedx.com]
Muscular Atrophy
  • Atrophy, X-Linked 2 Stormorken Syndrome Triosephosphate Isomerase Deficiency Usher Syndrome Vici Syndrome Williams Syndrome Wolfram Syndrome Xanthinuria, Type I X-Linked Intellectual Disability-Hypotonia-Facial Dysmorphism-Aggressive Behavior Syndrome[familydiagnosis.com]
  • atrophy Endocrine myopathy: Cushing’s syndrome Hyper or hypo- thyroidism Hyper- or hypo- parathyroidism Drug induced myopathy : True myositis: Penicillamine, Procainamide Zidovudine (a form of mitochondrial myopathy) Glucocorticoids Statins: Lovastatin[learningneurology.com]
  • atrophy Adrenomyeloneuropathy Recovery from severe malnutrition & weight loss Pectoral muscle hypertrophy Gonadal Disorders Dysgenesis Ataxia & Pyramidal syndrome : COX10 HMSN Minifascicles HSN Minifascicles & Mental retardation Hypogonadism Hereditary[neuromuscular.wustl.edu]
  • 末梢神経病変を主とする神経原性疾患 1) Charcot-Marie-Tooth病, peroneal muscular atrophy, HMSN I 症例16 Charcot-Marie-Tooth病 症例17 寒冷刺激に対する血管運動神経反射亢進を伴う常染色体性優性遺伝のCharcot-Marie-Tooth病 2) 肥厚性間質性神経炎, Dejerine-Sottas病, HMSN III 症例18 肥厚性間質性神経炎 3) HMSN II, 遺伝性運動感覚ニューロパチー type II,[molcom.jp]
  • atrophy Patient with autonomic dysfunction: Hepatitis B surface antigen positive hepatitis Myalgia Tachycardia EKG abnormalities Steroid responsiveness Genetic Defects of Long Chain Fatty Acid Oxidation Autosomal recessive lipid storage myopathy: AR[neurodiffdx.com]
Proximal Muscle Weakness
  • A 61-year-old woman had proximal muscle weakness since 38 years of age. Eventually, her distal muscles became affected and she showed widespread muscle wasting, absent tendon reflexes, and electromyographic findings of a neuropathy.[jamanetwork.com]
  • muscle weakness -difficulty rising from squatting position, getting up from chair •tender muscles to pressure •can progress rapidly with complications such as dysphagia and aspiration pneumonia •skin involvement eyes, chest, fingers Diagnosis •CK elevated[quizlet.com]
  • This particular form of late-onset mitochondrial myopathy is clinically characterized by insidious mild proximal muscle weakness, associated, in some cases, with easy fatigability.[academic.oup.com]
Suggestibility
  • These data suggest that the underlying biochemical abnormality in this patient may be a deficiency of the carnitine-acylcarnitine translocase system or a defective interaction between acyl-CoA dehydrogenase and its flavoprotein coenzyme.[ncbi.nlm.nih.gov]
  • L-carnitine administration and anaplerotic diet therapy with triheptanoin have been suggested for treatment of the disease; however benefits have not been proven. Prognosis The myopathic form of CPT II has a good prognosis.[orpha.net]
  • Necrotic and regenerating muscle fibres have occasionally been described after acute phases of deterioration in carnitine deficiency. 2 Lipid storage in combination with ragged-red fibres is suggestive of a respiratory chain defect with secondary carnitine[jnnp.bmj.com]
  • A connection between lipid storage myopathy and hyperlipoproteinemia was suggested.[jamanetwork.com]
  • Pregnancy and Breastfeeding Lack of evidence showing its safety in this population suggests avoiding supplemenation during pregnancy and nursing.[ndhealthfacts.org]
Kidney Failure
  • Carnitine Deficiency: Causes, Symptoms Causes [2] : Chronic kidney failure Vitamin C deficiency Medications: anticonvulsants (valproic acid), drugs used in AIDS (zidovudine [AZT)] didanosine [ddI], zalcitabine [ddC] and stavudine [d4T]), antibiotics ([nutrientsreview.com]
  • Secondary carnitine deficiencies may occur due to certain disorders (such as chronic renal failure- or kidney failure as it is known) or under particular conditions (e.g., use of certain antibiotics) that reduce carnitine absorption or increase its elimination[leadiant.com]
  • failure, respiratory insufficiency, and episodic abnormal heart rhythms.[en.wikipedia.org]
Paresis
  • Symptoms of the disease are muscle weakness, pain, convulsions, paresis, difficulty performing prolonged exercise, the formation of contractures. Diagnosis is based on history, research content of enzymes in the blood stream, muscle biopsy.[medicalformat.com]
  • Autoimmune/Infectious inflammatory) •Medication/Toxin induced •Systemic/Endocrine disease General on diagnostics/diff diag •Myopathies are distinguished from other neuromuscular weakness: -neuropathies, motor neuron disease, myasthenia gravis, LEMS -CLINICS: paresis[quizlet.com]
  • Autoimmune Target autoantigens Association with myasthenia gravis Frequency of MG when DO present: 1% clinical MG; 8% with anti-AChR antibodies Especially when Exotropia present Non-restrictive ophthalmoplegia New EOM paresis after period of stability[neuromuscular.wustl.edu]
  • A neurologic examination that shows deficits in a single nerve or radicular distribution indicates a possible mononeuritis, entrapment neuropathy, or radiculopathy, and calls for a different workup than that required for a limb paresis in a patient with[aafp.org]
Areflexia
  • Weakness Muscular Hypoplasia, Congenital Universal, of Krabbe Musculoskeletal Pain Myalgia myofascial pain syndrome Myopathic Carnitine Deficiency myopathy Myopathy with Giant Abnormal Mitochondria Myopathy with Lactic Acidosis, Hereditary Myopathy, Areflexia[rgd.mcw.edu]

Workup

The following diagnostic criteria have been established for any type of primary carnitine deficiency [3]:

  • Severe reduction of plasma or tissue carnitine levels
  • Evidence that the low carnitine levels impair fatty acid oxidation
  • Correction of the disorder when carnitine levels are restored
  • Absence of other primary defects in fatty acid oxidation

Blood samples as well as liver and skeletal muscle biopsy specimens must be obtained to confirm the selective deficiency of carnitine in muscle tissues. In MCD, circulating carnitine levels are within physiological ranges, as is the carnitine content of hepatic tissue. Skeletal muscle carnitine contents are reduced to about 20% of the normal values [7] [11]. Creatine kinase serum concentrations are generally increased. Beyond that, urine samples may be analyzed to determine the fractional renal excretion of carnitine. Renal wasting of carnitine is not a typical feature of MCD, but Vielhaber and colleagues described impaired renal reabsorption of carnitine in one of their patients [7].

Carnitine deficiency interferes with fatty acid catabolism by β-oxidation and results in an increased formation of triglycerides. Hence, the histological equivalent of MCD is that of a lipid storage myopathy with excess numbers of lipid droplets in muscle fibers predominately of type 1 at the light and electron microscopy level [7]. Carnitine-dependency can be shown by the addition of carnitine to muscle homogenates [2]: In the presence of carnitine, MCD muscle cells oxidize fatty acids at essentially the same rate as do those of healthy controls.

An exhaustive list of "other primary defects in fatty acid oxidation" that must be considered in the differential diagnosis of MCD cannot be provided. Such defects may affect the carnitine cycle or the β-oxidation cycle, which both rely on a number of enzymes: carnitine palmitoyl transferases I and II, carnitine-acylcarnitine translocase, acyl-CoA dehydrogenases that target fatty acids of varying chain length, 3-hydroxyacyl-CoA dehydrogenases, 3-ketoacyl-CoA thiolases, and 2,4-dienoyl-CoA reductase, to name but a few [3]. While disorders of carnitine transport and the carnitine cycle have been reviewed by Longo et al. [12], the interested reader is referred to the comprehensive overview published by Moczulski and colleagues to learn more about genetic disorders of β-oxidation [13].

Treatment

The dietary supplementation of carnitine has been shown to be beneficial [3] [7], although muscle carnitine stores cannot be replenished by the mere increase of oral carnitine intake. Here, carnitine deficiency is the consequence rather than the cause of the disease, and a greater supply of carnitine can have but little effect on the muscle carnitine content if the myocytes themselves are unable to take it up or to keep it.

The patient described by Engel and colleagues experienced clinical improvement under prednisone therapy [2]. Histological abnormalities became less pronounced but could not be rectified. What's more, the mechanism by which lipid storage diminished under prednisone remains unknown. The authors speculated the drug to have exerted its effect via a compensatory mechanism that can reduce muscle lipid levels independent of carnitine transport. While similar observations have been made in other patients [14], treatment with prednisone could not prevent the fatal outcome in a later case of MCD with cardiomyopathy [9].

Some patients have been prescribed special diets based on medium-chain triglycerides, which may contribute to the recovery of strength in the affected muscles [6] [11].

Prognosis

MCD generally follows a benign course. The resolution of clinical symptoms seams feasible despite the fact that muscle carnitine levels cannot be restored to physiological values [7]. Yet, the patients' response to carnitine supplementation varies largely and ranges from moderate improvement to the normalization of muscle strength [3]. In the rare case of cardiac involvement, the prognosis seems to be less favorable, and a fatal outcome is possible [11].

Etiology

Kerner and Hoppel explained that the distribution of carnitine in different tissues depends on a series of systems that transport carnitine into cells against a concentration gradient, that mediate its efflux, or facilitate an exchange mechanism [1]. They hypothesized MDC to be caused by an increased loss of muscle carnitine via defective efflux carriers. Others proposed a tissue-specific defect of short-chain acyl-CoA dehydrogenase as the cause of lipid storage myopathy and limb weakness [3]. To date, it remains unknown whether all patients who have been diagnosed with MCD suffered from the same disease or were carriers of distinct gene defects leading to phenotypically similar myopathies.

Although the underlying gene defect has yet to be determined, MCD is assumed to be inherited in an autosomal recessive pattern [11] [14]. This hypothesis is based on the fact that intermediate levels of muscle carnitine were measured in the parents of some MCD patients, suggesting an allele-dose effect for the causal mutation.

Epidemiology

MCD is a very rare disease. Since the initial description of MCD [2], about 100 cases with different forms of carnitine deficiency have been reported [1].

Sex distribution
Age distribution

Pathophysiology

Carnitine is an essential cofactor for the transport of activated long-chain fatty acids from the cytosol to the mitochondrial matrix, where β-oxidation takes place. Dietary intake and endogenous synthesis are the main sources of carnitine, which is efficiently reabsorbed in the renal tubules so as to maintain adequate levels of circulating carnitine [15].

  • Major sources of carnitine in the human diet are meat, fish and dairy products.
  • Carnitine is synthesized ultimately from the amino acids lysine and methionine, in a multi-step process involving several enzymes. The biosynthesis of carnitine may occur in the kidneys, liver, and brain.

Regardless of the source, carnitine must actively be transported into muscle cells. Thus, low concentrations of carnitine in the muscles may be due to deficiencies in carnitine intake, biosynthesis, reabsorption in the kidneys, or systemic distribution, or may be caused by specific disorders of plasma-to-muscle carnitine transport [7]. The former would be associated with low levels of circulating carnitine, while the latter is characterized by low muscle carnitine but physiological concentrations in the plasma and other tissues.

Gene defects interfering with carnitine biosynthesis have not yet been described. Generalized disorders of carnitine distribution and transmembrane transport, however, may occur and are associated with renal wasting of carnitine in patients with SCD. The selective deficiency of carnitine in muscle tissue is the hallmark of MCD.

Prevention

Due to considerable knowledge gaps regarding the etiology and pathogenesis of MCD, no recommendations can be given to prevent the disease.

Summary

MCD is a rare type of myopathy. It is also referred to as muscle carnitine deficiency and has first been described by Engel and Angelini in 1973 [2]. They wrote about a female patient in her early twenties who suffered from progressive muscle weakness. Histological studies revealed her muscle fibers to contain numerous lipid-filled vacuoles and led to the suspicion of a defect in the oxidative catabolism of fatty acids. This hypothesis could eventually be confirmed and related to low carnitine levels in the musculature. The molecular biological and genetic background of the disease has not been clarified, however.

This situation has not changed much until today. Some more cases have been reported during the 1970s [5] [14], but there are only anecdotal reports in the more recent literature. What's more, patients described so far cover a broad spectrum of phenotypes that ranges from the classical variant of sole skeletal muscle involvement to life-threatening cardiomyopathy, renal wasting of carnitine, and even peripheral neuropathy [Zhang], which blurs the distinction between MCD and SCD. The diagnosis of MCD has always been based on biochemical and histological abnormalities, but could never be associated with a precise cause. Thus, the correct classification of MCD remains unclear, and it may be doubted whether the same entity accounted for all cases reported to date.

Patient Information

Carnitine is derived from amino acids and required for the oxidation of fatty acids in mitochondria, the cell's supplier of energy. Humans cover their carnitine needs by diet and biosynthesis, and the compound is distributed throughout the body via systemic circulation. The uptake of carnitine by the cells is mediated by specific transporters, which account for it to finally reach the mitochondria. Accordingly, there are several circumstances that may result in cellular carnitine deficiency: a lack of carnitine intake, errors of carnitine biosynthesis or systemic distribution, or the unability of carnitine to cross cellular membranes, to name but a few.

If deficiencies in the cellular uptake of carnitine are limited to muscle cells, patients may experience progressive muscle weakness, increased muscular fatigability, and muscle pain, and they may be diagnosed with myopathic carnitine deficiency (MCD). There is no lack of carnitine supply or distribution, but a mere inability of muscle cells to capture carnitine from the plasma. This has diagnostic implications: In clinical practice, plasma levels of carnitine are commonly used to test for carnitine deficiency. These values, however, may not reflect tissue carnitine concentrations and are to be expected within the physiological range in patients with MCD. Muscle carnitine contents must be determined to confirm the suspicion of MCD. In affected individuals, they are decreased despite normal levels of plasma carnitine. Furthermore, skeletal muscle biopsies must be histologically examined for the presence of abnormal lipid storage. In the absence of carnitine, the oxidation of fatty acids is largely reduced, and lipids accumulate within muscle cells.

MCD is assumed to be a hereditary disorder, but the underlying gene defect could not yet be identified. Thus, the diagnosis of the disease is based on clinical, laboratory, and histological findings as described above. Carnitine supplementation is the mainstay of therapy, but patients respond differently to this type of treatment. Predisone and dietary adjustments may further contribute to the alleviation of symptoms, but the disease is currently not curable. In general, though, MCD follows a benign course.

References

Article

  1. Kerner J, Hoppel C. Genetic disorders of carnitine metabolism and their nutritional management. Annu Rev Nutr. 1998; 18:179-206.
  2. Engel AG, Angelini C. Carnitine deficiency of human skeletal muscle with associated lipid storage myopathy: a new syndrome. Science. 1973; 179(4076):899-902.
  3. Pons R, De Vivo DC. Primary and secondary carnitine deficiency syndromes. J Child Neurol. 1995; 10 Suppl 2:S8-24.
  4. Shapira Y, Gutman A. Muscle carnitine deficiency in patients using valproic acid. J Pediatr. 1991; 118(4 Pt 1):646-649.
  5. Markesbery WR, McQuillen MP, Procopis PG, Harrison AR, Engel AG. Muscle carnitine deficiency. Association with lipid myopathy, vacuolar neuropathy, and vacuolated leukocytes. Arch Neurol. 1974; 31(5):320-324.
  6. Martin JJ, Vercruyssen A, de Barsy T, Ceuterick C. Muscle carnitine deficiency in old age. Case report and therapeutic results. Clin Neurol Neurosurg. 1985; 87(4):275-281.
  7. Vielhaber S, Feistner H, Weis J, et al. Primary carnitine deficiency: adult onset lipid storage myopathy with a mild clinical course. J Clin Neurosci. 2004; 11(8):919-924.
  8. Colin AA, Jaffe M, Shapira Y, Ne'eman Z, Gutman A, Korman S. Muscle carnitine deficiency presenting as familial fatal cardiomyopathy. Arch Dis Child. 1987; 62(11):1170-1172.
  9. Cornelio F, Di Donato S, Testa D, et al. "Carnitine deficient" myopathy and cardiomyopathy with fatal outcome. Ital J Neurol Sci. 1980; 1(2):95-100.
  10. Hart ZH, Chang CH, Di Mauro S, Farooki Q, Ayyar R. Muscle carnitine deficiency and fatal cardiomyopathy. Neurology. 1978; 28(2):147-151.
  11. Angelini C, Trevisan C, Isaya G, Pegolo G, Vergani L. Clinical varieties of carnitine and carnitine palmitoyltransferase deficiency. Clin Biochem. 1987; 20(1):1-7.
  12. Longo N, Amat di San Filippo C, Pasquali M. Disorders of carnitine transport and the carnitine cycle. Am J Med Genet C Semin Med Genet. 2006; 142c(2):77-85.
  13. Moczulski D, Majak I, Mamczur D. An overview of beta-oxidation disorders. Postepy Hig Med Dosw (Online). 2009; 63:266-277.
  14. VanDyke DH, Griggs RC, Markesbery W, Dimauro S. Hereditary carnitine deficiency of muscle. Neurology. 1975; 25(2):154-159.
  15. Vaz FM, Wanders RJ. Carnitine biosynthesis in mammals. Biochem J. 2002; 361(Pt 3):417-429.
  16. Zhang W, Miao J, Zhang G, et al. Muscle carnitine deficiency: adult onset lipid storage myopathy with sensory neuropathy. Neurol Sci. 2010; 31(1):61-64.

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Last updated: 2019-08-16 17:32