Presented on September 9th, 2023.

Araya Puwanant, MD, MS
Wake Forest University School of Medicine, Winston Salem, North Carolina, United States

Myotonic dystrophy type 2 (DM2), an autosomal dominant muscular dystrophy, is characterized by late-onset progressive proximal muscle weakness, myotonia, and multisystem features. DM2 results from a CCTG repeat expansion in the cellular nucleic acid binding protein (CNBP) gene, where the RNA gain-of-function is considered the primary mechanism that leads to myopathy. Although muscle structure measures from magnetic resonance imaging (MRI) have been used to assess disease severity in other muscular dystrophies, relatively little is known about how these measures are affected in DM2. While major progress has been made in drug development in myotonic dystrophy type 1 (DM1), identifying sensitive biomarkers of disease severity is essential to inform future clinical trial design in DM2. This presentation will review various imaging modalities employed in studies of DM2, from muscle ultrasound and DXA regional body composition to advanced MRI. We will discuss the strengths and limitations of each imaging technique in capturing abnormalities of muscle structure and function. The talk will focus on the latest research findings on muscle MRI in patients with DM2 compared to the control and DM1 groups, how these findings correlate with clinical endpoints, and whether MRI measures could serve as sensitive biomarkers of disease progression in DM2. Finally, we will discuss our pilot data from the DM2 brain study and the role of white matter abnormalities facilitating motor dysfunction, which is already compromised by dystrophic muscle pathology in DM2.

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