Table 2.
Summary of myotonic dystrophy type 1 phenotypes, clinical findings and CTG length.
| Phenotypes | Clinical findings | CTG length | Age of onset |
|---|---|---|---|
| Congenital | Infantile hypotonia Respiratory failure Learning disability Cardiorespiratory complications |
> 1000 | Birth |
| Childhood onset | Facial weakness Myotonia Low IQ Conduction defects |
50-1000 | 1-10 years |
| Adult onset "classic DM1" | Weakness Myotonia Cataracts Conduction defects Insulin resistance Respiratory failure |
50-1000 | 10-30 years |
| Late onset/Asymptomatic | Mild myotonia Cataracts |
50-100 | 20-70 years |
| Pre-mutation | None | 38-49 | N/A |