Disease relevance of Glycogen Storage Disease Type V

• Inherited deficiency of myophosphorylase leads to glycogen storage disease type V (McArdle's disease) [1].
• Nine patients with McArdle disease, one with the partial glycolytic defect phosphoglycerate mutase deficiency, and nine matched, healthy subjects performed the classic ischemic forearm protocol and an identical protocol without ischemia [2].
• Noncardiogenic pulmonary edema and rhabdomyolsis after protamine administration in a patient with unrecognized McArdle's disease [3].
• Worsening myopathy associated with ezetimibe in a patient with McArdle disease [4].
• Pretreatment with glucagon relieved patients with McArdle disease from muscular symptoms during exercise and enhanced exercise performance, though it did not produce any improvement in patients with Tarui disease [5].

High impact information on Glycogen Storage Disease Type V

• Molecular genetic heterogeneity of myophosphorylase deficiency (McArdle's disease) [6].
• McArdle's disease is genetically heterogeneous, but the most common mutation is the substitution of thymine for cytosine at codon 49 [6].
• Molecular mechanisms of McArdle's disease (muscle glycogen phosphorylase deficiency). RNA and DNA analysis [7].
• Intravenous glucose administration increased maximal oxygen uptake about 20% in those with McArdle's disease, but both VO2max and R remained lower than in control subjects [8].
• Our results show that in McArdle's disease the exerted force is less, the surface EMG (SEMG) amplitude steadily increases, and that the power density spectrum (PDS) shifts to lower frequencies, the latter without significant differences when compared with normals [9].

Chemical compound and disease context of Glycogen Storage Disease Type V

• We measured purine degradation products of ATP in plasma after ischemic exercise in eight normal subjects, one patient with myophosphorylase deficiency (McArdle's disease), and one with carnitine palmityltransferase deficiency [10].
• 2,4-Dinitrophenol, muscle biopsy, and McArdle's disease [11].
• Two different forms of myophosphorylase deficiency (McArdle's disease) can be distinguished through the presence or absence of the protein subunit corresponding to phosphorylase in muscle extracts analyzed by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis [12].
• RESULTS: In contrast to patients with McArdle disease, with whom they share many clinical features, in patients with PGAMD, cycle exercise and oxidative capacity are virtually normal, a second wind does not occur, and lipid and lactate supplements do not improve exercise capacity [13].
• BACKGROUND: In a recent study, we showed that administration of low-dose creatine (Cr) (60 mg/kg daily) improved work capacity in patients with McArdle disease [14].

Biological context of Glycogen Storage Disease Type V

• Two novel missense mutations (E654K, L396P) in Caucasian patients with myophosphorylase deficiency (McArdle's disease) [15].
• Homozygosity by descent for a rare mutation in the myophosphorylase gene is associated with variable phenotypes in a Druze family with McArdle disease [16].
• 4. In conclusion, changes in muscle interstitial lactate and ammonia concentrations during and after exercise are temporally dissociated from changes in MSNA and blood pressure in both patients with McArdle's disease and healthy control subjects [17].
• OBJECTIVE: To investigate the degree of genetic heterogeneity of myophosphorylase deficiency (McArdle disease) in Spain through molecular studies of 10 new patients [18].
• Muscle fatigue in McArdle's disease studied by 31P-NMR: effect of glucose infusion [19].

Anatomical context of Glycogen Storage Disease Type V

• We analyzed leukocyte DNA from 32 patients with suspected McArdle's disease, 24 of whom had biochemically or histochemically proven myophosphorylase deficiency [20].
• Myophosphorylase gene transfer in McArdle's disease myoblasts in vitro [21].
• This case demonstrates that the ischaemic lactate-ammonia test still has a place in screening patients with symptoms suggestive of McArdle's disease and emphasizes the importance of carrying out glycogen phosphorylase histochemistry on the skeletal muscle biopsy to confirm the diagnosis [22].
• Peripheral nerve and vasculature involvement in myophosphorylase deficiency (McArdle's disease) [23].

Gene context of Glycogen Storage Disease Type V

• Resolution of a mispaired secondary structure intermediate could account for a novel micro-insertion/deletion (387 insA/del 8 bp) in the PYGM gene causing McArdle's disease [24].
• Two patients showed a defect of PPL in muscle, and were homozygous for the most common mutation associated with McArdle's disease, R49X in the muscle PPL gene (PYGM) [25].
• McArdle's disease with myoadenylate deaminase deficiency: observations in a combined enzyme deficiency [26].
• However, muscle phosphorylase gene structure and expression appear to be unaltered in mdf/mdf mice, indicating that this mutation is not an animal model for the human genetic disorder McArdle's disease [27].
• McArdle's disease is an autosomal recessive myopathy with symptoms of exercise intolerance caused by deficiency of the enzyme muscle glycogen phosphorylase which releases glucose for contraction during exercise [28].

Analytical, diagnostic and therapeutic context of Glycogen Storage Disease Type V

• To determine if lactic acid is a critical mediator of metaboreflex activation in humans, we performed microelectrode recordings of MSNA in eight patients with myophosphorylase deficiency (McArdle's disease) who cannot metabolize intramuscular glycogen and do not generate lactic acid in exercising muscles [29].
• Eleven patients, comprising three cases of McArdle's disease and eight with an exertional muscle pain syndrome (EMPS) of unknown cause, entered a double-blind crossover study of verapamil and placebo [30].
• The ischaemic exercise test with measurement of plasma inosine and hypoxanthine might be of diagnostic value in MADD, but not in McArdle's disease [31].

References