Variant repeat interruptions and clinical outcomes in myotonic dystrophy type 1


  • Variant repeat (VR) interruptions were associated with later onset and milder disease phenotype in people with myotonic dystrophy type 1 (DM1), but not with clinical outcomes following cognitive behavioral therapy (CBT).

Why this matters

  • DM1 is an autosomal dominant neuromuscular disorder caused by expansion of unstable CTG repeats in the DMPK gene. VR interruptions within the CTG repeats – most commonly by CCG motifs – have previously been linked to different clinical phenotypes of DM1.

  • Key drivers of poor health status in DM1 include chronic fatigue, reduced initiative, and weak social interactions and the OPTIMISTIC trial (NCT02118779) found that CBT significantly improved clinical outcomes. However, it was unknown if outcomes following CBT intervention were similar between people with and without VR interruptions.