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Cardiomyopathy
Published in Charles Theisler, Adjuvant Medical Care, 2023
Primary carnitine deficiency (PCD) is an inherited disorder in which patients affected with the disease may present with acute metabolic decompensation during infancy or with severe cardiomyopathy in childhood. Treatment of this disorder with L-carnitine is highly effective in correcting cardiomyopathy and muscle weakness, as well as any impairment in fasting ketogenesis.
Carnitine transporter deficiency
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop
The inborn errors of fatty acid oxidation, including carnitine transporter deficiency (CTD) [1, 2], represent a relatively recently recognized area of human disease. The rate of discovery of distinct disorders has increased rapidly since the discovery of medium-chain acyl CoA dehydrogenase (MCAD) deficiency in 1982 (Chapter 39). Deficiency of carnitine is common in these disorders in which fatty acyl CoA compounds accumulate which then form esters with carnitine and are preferentially excreted in the urine. Carnitine deficiency may also be profound in organic acidemias, such as propionic acidemia, for the same reason. The transport of carnitine into fibroblasts is inhibited by long- and medium-chain acylcarnitines [3], and this may be an additional factor in carnitine deficiency in disorders of fatty acid oxidation. Primary carnitine deficiency resulting from an abnormality in the synthesis of carnitine from protein-bound lysine has not yet been observed. Many of the patients reported early as primary carnitine deficiency have turned out to have MCAD deficiency. Deficiency of carnitine as a result of abnormality in the transporter (Figure 35.1) that facilitates its entry into certain cells has been referred to as primary carnitine deficiency [1]. The carnitine transporter is an organic cation transporter (OCTN2) in the solute carrier family. The gene SLC22A5 has been cloned, and increasing numbers of mutations are being found [4–6].
Diseases of Muscle and the Neuromuscular Junction
Published in John W. Scadding, Nicholas A. Losseff, Clinical Neurology, 2011
Chris Turner, Anthony Schapira
Primary carnitine deficiency may be associated with a myopathy and is caused by defective carnitine uptake. It may be diagnosed in skin fibroblasts or blood leukocytes. Patients respond to carnitine supplementation. Secondary carnitine deficiency occurs in some patients with respiratory chain defects, acyl CoA dehydrogenase deficiencies and methylmalonyl CoA mutase deficiency. Sodium valproate may also deplete carnitine stores. Carnitine-deficient myopathy usually presents in childhood or adolescence with proximal limb weakness, although facial and bulbar weakness may also occur. Muscle biopsy may show increased accumulation of lipid, especially in type 1 fibres.
Diagnostic challenges in metabolic myopathies
Published in Expert Review of Neurotherapeutics, 2020
Corrado Angelini, Roberta Marozzo, Valentina Pegoraro, Sabrina Sacconi
Most patients with primary carnitine deficiency are followed by a metabolic specialist as well as a dietician., it has been documented that the main treatment with carnitine supplementation corrects heart problems and muscle weakness [25,43] in several patients. In some cases, this treatment prevents the need for a cardiac transplant. The L – carnitine dose may vary from 100 to 600 mg/kg per day based on the calculated carnitine depletion from tissues. To adjust the dose, several plasma carnitine level measurements might be useful, Plasma carnitine levels should be monitored frequently to reduce the episodes of hypoglycemia. Side effects for L – carnitine supplementation are mild and consist of diarrhea, intestinal discomfort, or a fishy body odor. In some cases, a medium-chain triglyceride diet (MCT) may be added. Muscle carnitine clinical features affect mostly limb and neck muscles. The patients show normal ketogenesis on fasting. Diagnostic biochemical features are low muscle carnitine (below 15%) and absence of organic aciduria. There is in vitro stimulation by L-carnitine of labeled palmitate oxidation and oleate [24]. Muscle carnitine deficiency could be caused by an abnormal low – affinity carrier or by a low number of sarcolemmal carriers. It is differentiated from carnitine insufficiency in FAO disorders because of the absence of acylcarnitines elevation in plasma or urine.