Congenital myotonic dystrophy. Incidence, clinical aspects and early prognosis.

Congenital myotonic dystrophy (CMD) is characterized by hypotonia, facies myopathica, feeding and respiratory problems, skeletal deformities and polyhydramniosis. It is an autosomal-dominant disorder transmitted via the mother. The diagnosis can as a role be confirmed by examining the mother, but can fail as she might be asymptomatic. During a nine year period, eight children were diagnosed as CMD which means an incidence of one case per approximately 3,500 live births. The diagnosis was confirmed in six of the mothers. The two floppy infants, where positive inheritance could not be proven, showed most of the signs and symptoms described in CMD. Four children died, two from respiratory insufficiency and two suddenly and unexpectedly. CMD may be one less common cause of sudden infant death syndrome (SIDS). The four children who survived displayed delayed psychomotor development.