Congenital myotonic dystrophy: a retrospective study of a single center

Congenital myotonic dystrophy (DMC) is an autosomal dominant disorder caused by trinucleotide repeat expansion of cytosine-thymine-guanine in the 3’ untranslated region of the dystrophia myotonica protein kinase gene. It is exclusively transmitted through the maternal line. Seventeen children diagnosed with DMC by molecular genetic testing were retrospectively analyzed. Eight children were male, and nine were female. Age at diagnosis was between 1 month and 16 years. The most common complaint of children younger than 1 year of age was hypotonia and respiratory distress. Children over the age of 10 were unable to open their hands. The mothers of 11 patients had clinical myotonia. Seven were followed in the neonatal intensive care unit, 5 were hypotonic, and 5 had respiratory distress during this period. Mental development of 5 children was normal. Nine of them had mild, 2 had moderate, and 1 had severe mental retardation. Walking age ranged from 14 months to 4 years. Muscle hypertrophy or kyphoscoliosis was observed in none. Four children had joint contractures. A high-arched palate was observed in 14 cases, 1 had dysphagia. Three children had constipation. Creatine kinase values ranged from 88-269 u/l. DMC should be considered in the differential diagnosis of newborns with a history of respiratory assistance in the neonatal intensive care unit, hypotonia, high-arched palate, global muscle weakness, and mental developmental delay. Duration of artificial ventilatory support during the first few months of life denotes prognosis. Family history, especially myotonia in mothers, is essentialwhich is required for genetic counseling.
Keywords: myotonia congenita dystrophica, clinical features