Course, prognosis and complications of childhood-onset myotonic dystrophy.

The outcome for 71 patients with childhood-onset myotonic dystrophy was examined. In addition to 18 patients with later onset, but presenting in childhood, and 46 with the congenital form, seven patients from congenital sibships who did not present in the neonatal period were found to have myotonic dystrophy of intermediate severity. The incidence of the congenital form in South Wales was six per 100,000. In all groups the mortality rate was low after the perinatal period. The prognosis for normal family life and ultimate gainful employment was poor. Testicular atrophy in congenitally affected males was evident at puberty, and there was a high incidence of gastro-intestinal problems. The contributions of deafness as a result of recurrent otitis, and of severe articulation defects, should be considered when assessing the degree of mental handicap.