Prevalence of LOPD in patients with undifferentiated proximal myopathy and undiagnosed muscle biopsy

 Study objective and method

Results

Baseline characteristics of patients with unclassified LGMW

Clinical and laboratory data of patients with unclassified LGMW

Diagnostic yield of LOPD: 2/69 (2.9%)

Patient 1		Patient 2
A 22-year–old Caucasian female with the chief complaint of muscular exertion intolerance associated with muscle aches and cramps.	Patient profile	A 29-year–old Caucasian male with atrophies of the shoulder, pelvic girdle, and paravertebral muscles. Predominantly left-sided scapula alata and positive Gower’s sign.
Completely unspecific myopathic changes with evidence of small lipid droplets	Muscle biopsy	Suspicious changes associated with Pompe disease Vacuolated muscle fibers Glycogen storage with enhanced lysosomal activity
No signs of HCM, FVC: <80%	Other findings	No signs of HCM, FVC: 72%

LOPD not only demonstrates wide variability in the clinical phenotype but also in the histopathological changes in the skeletal muscles.

Conclusion

• Revisiting muscle biopsies is important in neuromuscular disease diagnosis.
• Muscle biopsy can aid in LOPD identification, but glycogen-related vacuolation can be absent.
• An inconclusive muscle biopsy does not rule out Pompe disease.
• DBS evaluation should precede muscle biopsy for all LGMW patients