McArdle disease: 2 case reports

Area of Science:

• Neurology
• Metabolic Disorders
• Clinical Diagnostics

Background:

• Elevated serum creatine kinase (CK) levels frequently necessitate specialist referral.
• Myopathies represent a significant category of conditions causing increased CK.
• McArdle disease is identified as the most prevalent skeletal muscle carbohydrate metabolism disorder.

Observation:

• Two patients, a 72-year-old asymptomatic male and a 30-year-old female with mild symptoms, were evaluated for elevated CK.
• Both patients presented with normal electromyography results.
• Muscle biopsy revealed a complete absence of myophosphorylase activity in both individuals.

Findings:

• The diagnostic evaluation confirmed McArdle disease in both patients.
• Null myophosphorylase activity is a key indicator for McArdle disease diagnosis.
• The study highlights the utility of enzyme activity assays in muscle biopsies for diagnosing metabolic myopathies.

Implications:

• This case series underscores the importance of investigating elevated CK levels, even in asymptomatic individuals.
• Early diagnosis of McArdle disease allows for appropriate patient management and genetic counseling.
• Understanding the clinical spectrum of McArdle disease aids in differential diagnosis for unexplained myopathies.