[Congenital myotonic dystrophy--the significance of a handshake]

Three neonates, all girls, were presented immediately after birth with severe hypotonia. Two of them needed artificial ventilation because of respiratory insufficiency. All three pregnancies had been complicated by reduced fetal movements and moderate cerebral ventricular dilatation and in two of the three there was also polyhydramnios and congenital talipes. In all three infants congenital myotonic dystrophy was suspected after diagnosing myotonia in the mother. This was done by observing that none of the mothers were unable to release their grip immediately on command after shaking hands. Ophthalmological examination of the women revealed polychromatic lens crystals characteristic of myotonic dystrophy. Congenital myotonic dystrophy was confirmed by DNA analysis, as well as myotonic dystrophy in the mothers. All had an expansion of the number of cytosine-thymine-guanine(CTG)-trinucleotides in a part of the myotonic dystrophy protein-kinase gene. The first two infants died after 2 days and 15 months respectively.