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[McArdle disease: differential diagnosis of the increase in creatine kinase induced by the exercise test]
E Frick1, F W Reutter, B Weder
1Medizinische Klinik B, Kantonsspital St. Gallen.
Insights
McArdle's disease, a genetic disorder affecting glycogen metabolism, was diagnosed in a Turkish family. Early diagnosis and genetic counseling are crucial for autosomal recessive conditions like this glycogen storage disease.
Area of Science:
- Biochemistry
- Genetics
- Neurology
Background:
- McArdle's disease (glycogen storage disease type V) is an autosomal recessive metabolic disorder.
- It results from deficiency of muscle glycogen phosphorylase (myophosphorylase).
- This leads to impaired glycogen breakdown in muscles, causing exercise intolerance.
Observation:
- A Turkish couple presented with atypical precordial pain, muscle pain, and elevated creatine kinase after exertion.
- Characteristic symptoms of McArdle's disease were elicited upon specific questioning.
- Affected individuals included both parents and their two male children.
Findings:
- Diagnostic confirmation included a pathological ischemic forearm work test and serial stimulation test.
- Muscle biopsy revealed deficient myophosphorylase activity and abnormal glycogen content.
- Phosphor nuclear resonance confirmed the diagnosis in the children.
Implications:
- Consanguinity in an isolated community contributed to the high prevalence of this autosomal recessive condition.
- Highlights the importance of detailed patient history and specific diagnostic tests for rare genetic disorders.
- Suggests the need for genetic counseling and screening in families with suspected McArdle's disease.
Abstract:
In a Turkish couple presenting atypical precordial pain, muscle pain and a massive increase of creatine kinase during and one day after bicycle ergometry, suspicion of McArdle's disease was confirmed by a pathologic ischemic forearm worktest, a pathologic serial stimulation test and by pathologic glycogen content with lack of myophosphorylase activity on histochemical examination of thigh muscle tissue. Characteristic signs of McArdle's disease such as muscle weakness, muscle pain and muscle swelling, especially after exertion, were detected only after specific questioning of the patients. McArdle's disease was also detected by phosphor nuclear resonance in the two male children. Frequent consanguinity in the small isolated mountain village where the family originated explains why all four members of two generations are affected by the autosomal recessive disease.