Myotonic Muscular Dystrophy Type 2 in CT, USA: A Single-Center Experience With 50 Patients

Area of Science:

• Neurology
• Genetics
• Pathology

Background:

• Myotonic dystrophy type 2 (DM2) is an autosomal dominant disorder linked to (CCTG)n repeat expansions in the CNBP gene.
• DM2 is less frequent than Myotonic dystrophy type 1 (DM1).

Purpose of the Study:

• To report clinicopathologic findings in 50 DM2 patients over 27 years.
• To analyze the correlation between clinical presentation, genetic factors, and muscle pathology in DM2.

Main Methods:

• Retrospective analysis of 50 patients diagnosed with DM2.
• Clinical assessment, electromyography, and muscle biopsy review.
• Correlation analysis between CCTG repeat size, clinical symptoms, and pathological findings.

Main Results:

• DM2 presented with symptom onset between 15-72 years; diagnosis delay averaged 7.4 years.
• Proximal lower extremity weakness was the initial symptom in 62%; 18% had clinical myotonia, 97% had myotonic discharges on EMG.
• No correlation found between CCTG repeat size and clinicopathologic features; limb weakness correlated with muscle pathology.
• 12% had cardiac abnormalities; a 1% annual decline in Medical Research Council score was observed in followed patients.

Conclusions:

• DM2 exhibits variable clinical severity, with limb weakness and EMG findings being prominent.
• Muscle pathology correlates with weakness, but CCTG repeat size does not predict disease characteristics.
• Cardiac involvement and slow functional decline necessitate long-term monitoring in DM2 patients.