Which statement about myotonic dystrophy is true?

• A. Life expectancy is always normal
• B. Congenital form is more severe with hypotonia and respiratory issues at birth
• C. It only affects ocular muscles
• D. Onset occurs only in childhood

Answer: (B)

Myotonic dystrophy is a multisystem genetic dystrophy, most often caused by a CTG repeat expansion in the DMPK gene. The hallmark features are myotonia (delayed muscle relaxation) and progressive muscle weakness, with a spectrum from congenital to adult-onset forms. The congenital form is the most severe, and its presentation at birth includes marked hypotonia and respiratory difficulties, sometimes requiring ventilation. This is why the statement about the congenital form being more severe with hypotonia and respiratory issues at birth is true.

Life expectancy isn’t necessarily normal across all cases; the congenital form and other systemic involvement can lead to complications, including respiratory and cardiac problems, which can affect longevity. The disease also isn’t limited to ocular muscles; eye issues like ptosis and cataracts can occur, but many other muscles and organ systems are involved. And onset isn’t restricted to childhood—DM can begin in infancy, childhood, or adulthood, with congenital, juvenile, and adult presentations.