Three cases with early-onset myotonic dystrophy (MyD) belonging to different families are presented. This condition makes its appearance in the newborn period with symptoms such as difficulty in sucking and swallowing, facial diplegia, generalized muscular hypotonia, talipes equinovarus, and later a delay of psychomotor and language development. Sucking and swallowing difficulties may subside after some weeks; the muscular hypotonia may persist for a long time. Tendon reflexes are active or brisk, even in cases with most pronounced hypotonia. Signs of classical MyD may not develop until later childhood; muscle histology and electromyogram results are usually normal in the beginning but show typical changes later on.
Early-onset MyD has so far been observed exclusively in offspring of mothers who themselves carry the mutant gene.
Zellweger H, Ionasescu V. Early Onset of Myotonic Dystrophy in Infants. Am J Dis Child. 1973;125(4):601–604. doi:10.1001/archpedi.1973.04160040097021