Assessing population-based prevalence of myotonic dystrophy type 1


  • Individuals with CTG repeat expansions in the myotonic dystrophy type 1 (DM1)-associated DMPK gene are up to five times more prevalent than in previously reported estimates.

Why this matters

  • DM1 (genetic disorder characterized by delayed muscle reaction and/or weakness and other multisystemic manifestations) results from a non-coding CTG repeat expansion in the DMPK gene, with ≥50 repeats constituting a DM1 diagnosis, and 35-49 repeats considered a transmissible premutation. Current prevalence of DM1 is thought to be underestimated.

  • Greater-than-estimated CTG repeat expansion prevalence rates highlight the importance of population-based screening for DM1, which may not manifest clinically until later disease stages, potentially allowing for early management strategies for affected individuals.