Myopathies causing

This disease is one of several myopathies caused by defects in the... 

Phosphorylase deficiency (McArdle s disease, glycogenosis type V) is an autosomal recessive myopathy caused by a genetic defect of the muscle isoenzyme of glycogen phosphorylase (Fig. 42-1). Intolerance of strenuous exercise is present from childhood, but usually onset is in adolescence, with cramps after exercise [1, 5]. Myoglobinuria occurs in about one-half of patients. If they avoid intense exercise, most patients can live normal lives however, about one-third of them develop some degree of fixed weakness, usually as a late-onset manifestation of the disease. In a few patients, weakness rather than exercise-related cramps and myoglobinuria characterizes the clinical picture. 

Phosphoglycerate mutase deficiency is an autosomal recessive myopathy caused by a genetic defect of the muscle subunit of the enzyme PGM (type X, Fig. 42-1). 12 patients with this enzyme deficiency have been identified thus far. 

Defects of complex IV. These disorders, also termed COX deficiency, have clinical phenotypes that fall into two main groups one in which myopathy is the predominant or exclusive manifestation and another in which brain dysfunction predominates (Fig. 42-3). In the first group, the most common disorder is fatal infantile myopathy, causing generalized weakness, respiratory insufficiency and death before age 1 year. There is lactic acidosis and renal dysfunction, with glycosuria, phosphaturia and aminoaciduria, also termed DeToni-Fanconi-Debre syndrome. The association of myopathy and cardiopathy in the same patient and myopathy and liver disease in the same family has also been described [14]. 

Myopathy caused by drug interactions The incidence and severity of myopathy are increased by concomitant administration of HMG-CoA reductase inhibitors with drugs that can cause myopathy when given alone, such as gemfibrozil and other fibrates, and lipid-lowering doses (greater than or equal to 1 g/day) of niacin (nicotonic acid). 

A local myopathy caused by inhaled glucocorticoids can also cause dysphonia. However, patients with asthma have more dysphonia and vocal fold pathology than healthy controls and inhaled glucocorticoids can improve the voice in some patients (SEDA-21,188). 

Karpati, G., Charuk, J., Carpenter, S., Jablecki, C., and Holland, P., 1986, Myopathy caused by a deficiency of Ca2+-adenosine triphosphatase in sarcoplasmic reticulum (Brody s disease). Ann Neurol, 20 38—49. 

Ilkovski, B., Cooper, S. T., Nowak, K., Ryan, M. M., Yang, N., Schnell, C., et al. (2001) Nemaline myopathy caused by mutations in the muscle alpha-skeletal-actin gene. Am J Hum Genet 68, 1333-1343. 

Ishihara H, Kanda F, Matsushita T, Chihara K, Itoh K. White muscle disease in humans myopathy caused by selenium deficiency in anorexia nervosa under long term total parenteral nutrition. J Neurol Neurosurg Psychiatry 1999 67(6) 829-30. 

Dalakas MC, Ilia I, Pezeshkpour GH, Laukaltls JP, Cohen B, Griffin JL. Mitochondrial myopathy caused by long-term zidovudine therapy. N Engl J Med 1990 322 1098-1105. 

Only three cases of aldolase deficiency have been described. Beutler et aF have described a boy with an unstable enzyme with mental retardation and hemolytic anemia and dysmorphic features. Kishi et al described a patient with severe hemolytic anemia, exacerbated by infection, but none of the features described by Beutler et al. Kishi identified the mutation, leading to a conversion of aspartic acid at position 128 to glycine. Kreuder et ai reported on a boy with hemolytic anemia and myopathy caused by aldolase A deficiency. They identified a mutation, causative of an amino acid substitution at position 206 (Glu to Lys). 

If the phosphorylase pool plays an important part in vitamin B6 kinetics, it might be anticipated that this metabolism would be disturbed in patients suffering from MciVdle s disease, a rare metabolic myopathy caused by an absence of functional muscle glycogen phosphorylase. The absence of this enzyme means that patients cannot break down their muscle glycogen reserves. Other energy sources within the muscle are rapidly depleted... 

A 66-year-old man hospitalised for severe abdominal pain had been previously treated for chronic renal failure and was treated with sodium polystyrene sulphonate and the spherical carbon adsorbent AST-120 [105 ]. The diagnosis was h5rpokalemic myopathy caused by accumulation of sodium polystyrene sulphonate in the colorectum. 

Drosophila and mouse models of hereditary myopathy caused by mutations in yCP/p97... 

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