Myotonia congenita and myoadenylate deaminase deficiency: case report

Scola, Rosana Hermínia; Iwamoto, Fábio M.; Camargo, Carlos Henrique Ferreira; Arruda, Walter Oleschko; Werneck, Lineü Cesar

doi:10.1590/s0004-282x2003000200019

Cited by 1 publication

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“…There are even reports of AMPD1-deficient patients presenting with postexertional myoglobinuria 124 and rhabdomyolysis. 125,126 MADA deficiency has been shown to coexist with other disorders of nerve and muscle such as myotonia congenita, 127 McArdle disease, 128 some of the muscular dystrophies, 129 and myasthenia gravis, 120 raising the possibility that primary and secondary forms of AMPD1 exists. However, a recent study has found no significant increase in the frequency of AMPD1 mutations in patients with neuromuscular disease compared with controls.…”

Section: Clinical Featuresmentioning

confidence: 99%

Metabolic Myopathies: Update 2009

Adel¹,

Tarnopolsky²

2009

Journal of Clinical Neuromuscular Disease

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Metabolic myopathies are inborn errors of metabolism that result in impaired energy production due to defects in glycogen, lipid, mitochondrial, and possibly adenine nucleotide metabolism. Fatty acid oxidation defects (FAOD), glycogen storage disease, and mitochondrial myopathies represent the 3 main groups of disorders, and some consider myoadenylate deaminase (AMPD1 deficiency) to be a metabolic myopathy. Clinically, a variety of neuromuscular presentations are seen at different ages of life. Newborns and infants commonly present with hypotonia and multisystem involvement (liver and brain), whereas onset later in life usually presents with exercise intolerance with or without progressive muscle weakness and myoglobinuria. In general, the glycogen storage diseases result in high-intensity exercise intolerance, whereas the FAODs and the mitochondrial myopathies manifest predominately during endurance-type activity or under fasted or other metabolically stressful conditions. The clinical examination is often normal, and testing requires various combinations of exercise stress testing, serum creatine kinase activity and lactate concentration determination, urine organic acids, muscle biopsy, neuroimaging, and specific genetic testing for the diagnosis of a specific metabolic myopathy. Prenatal screening is available in many countries for several of the FAODs through liquid chromatography-tandem mass spectrometry. Early identification of these conditions with lifestyle measures, nutritional intervention, and cofactor treatment is important to prevent or delay the onset of muscle weakness and to avoid potential life-threatening complications such as rhabdomyolysis with resultant renal failure or hepatic failure. This article will review the key clinical features, diagnostic tests, and treatment recommendations for the more common metabolic myopathies, with an emphasis on mitochondrial myopathies.

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