Schwartz-Jampel syndrome with autosomal-dominant inheritance.

A 4-year follow-up study of 2 brothers affected by Schwartz-Jampel syndrome is reported. The children, aged 16 and 7 years, respectively, showed the clinical and electromyographical signs of the disorder. Further investigation showed some typical facial features of the syndrome, percussion myotonia and abnormal EMG pattern characterized by continuous muscle activity at rest in 3 other members of the same family. On the basis of our data, we suggest that inheritance of the Schwartz-Jampel syndrome may not only be recessive, as reported by most authors, but also dominant, with a different clinical expression.