Search for Pompe disease among patients with undetermined myopathies

Area of Science:

• Neurology
• Metabolic Disorders
• Genetics

Background:

• Pompe disease, a rare glycogen storage disorder, presents as limb-girdle muscle weakness in adults.
• Muscle biopsy may not always reveal the characteristic vacuolar myopathy, potentially leading to missed diagnoses.
• The study aimed to identify previously undiagnosed Pompe disease cases in western Sweden.

Purpose of the Study:

• To determine the prevalence of undiagnosed Pompe disease in western Sweden.
• To assess the utility of the dry blood spot test in identifying potential Pompe disease cases within a broader myopathy population.

Main Methods:

• A retrospective search of 3665 muscle biopsies (1986-2006) and inclusion of patients with unspecified myopathy or limb-girdle muscular dystrophy from a Neuromuscular Center.
• Application of the dry blood spot test to identify patients with Pompe disease.
• Follow-up testing, including GAA enzyme activity in lymphocytes and genetic analysis, for ambiguous results.

Main Results:

• Out of 82 evaluated patients, no individuals were diagnosed with Pompe disease.
• Three patients initially showed low dry blood spot test results, but subsequent lymphocyte enzyme activity tests were normal.
• Twelve patients (14.6%) received a definite molecular diagnosis for other myopathies after re-evaluation.

Conclusions:

• The prevalence of Pompe disease in western Sweden is estimated at 0.24 per 100,000 inhabitants, which is lower than in other reported regions.
• Re-evaluating patients with undiagnosed myopathies is clinically valuable, as demonstrated by the identification of alternative molecular diagnoses in a significant portion of the study cohort.