Novel mutation in the PYGM gene resulting in McArdle disease.
BACKGROUND
McArdle disease is a common metabolic disorder characterized by marked exercise intolerance, premature fatigue during exertion, myalgia, and cramps. Despite the wide knowledge of the molecular basis of McArdle disease, few studies have used a physiological approach or explored the possibility of improving the exercise capacity of these patients.


OBJECTIVE
To describe 3 unrelated patients with McArdle disease with a novel mutation in the PYGM gene and to assess the physical capacity in 1 of them.


METHODS
Using molecular genetic approaches, we identified the underlying molecular defect in 3 patients with McArdle disease. Physical performance was evaluated in 1 patient by means of an exercise tolerance test on a bicycle ergometer.


METHODS
Two university hospitals. Exercise physiology studies were performed in a university department. Patients The 3 patients showed common features of McArdle disease. They were definitively diagnosed by histochemistry, biochemistry, or molecular genetic analysis.


RESULTS
All of the 3 patients were genetic compounds for the common Arg50Stop mutation and a novel c.13_14delCT mutation in the PYGM gene. The peak oxygen uptake (VO(2peak)) of the patient who performed the exercise test was only 20.2 mL x kg(-1) x min(-1).


CONCLUSIONS
Together with the novel mutation, there is a markedly decreased exercise capacity in a patient with McArdle disease, which could account for the profound alteration in the capacity for performing normal activities of daily living in this subpopulation.
Rubio
Juan C
JC
Centro de Investigación and Servicio de Neuropatología, Hospital Universitario 12 de Octubre, Madrid, Spain.
Lucia
Alejandro
A
Fernández-Cadenas
Israel
I
Cabello
Ana
A
Blázquez
Alberto
A
Gámez
Josep
J
Andreu
Antoni L
AL
Martín
Miguel A
MA
Arenas
Joaquin
J
D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D004562:Electrocardiography; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D024981:Glycogen Phosphorylase / Q000235:genetics*; D006012:Glycogen Storage Disease Type V / Q000235:genetics*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D009154:Mutation / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D024981:Glycogen Phosphorylase