Abstract This study investigated reading and spelling difficulties in subjects with the juvenile form of myotonic dystrophy (MD). Twenty-three consecutive patients with juvenile MD who were referred to a special clinic were assessed for reading and spelling skills (phonological processing, word identification, narrative comprehension (two tasks), information seeking in a document (TV schedule), and spelling). Reading impairments were frequent (63-84% of the subjects being below the level of literacy depending on the tasks), even in subjects without mental retardation (22-66%) despite normal word identification scores. All but two subjects had spelling difficulties. The severity of these learning difficulties was correlated with longer mutation size and maternal transmission, but could not be related to phonological deficit, suggesting that other brain dysfunction might be involved (e.g., attention, working memory, naming speed, executive function). Children with the juvenile form of MD should systematically be assessed for reading and spelling problems, and correlations with basic cognitive functioning explored.
