Myotonic dystrophy: a report of two cases from one family

The authors report two cases of a brother and sister who suffered myotonic dystrophy and had a family history of the disease. Muscular dystrophy--more severe in the boy and mild in the girl--was the clinical manifestation. EMG findings corresponded to a primary muscle disorder, coinciding with myotonic activity in case 1. The genealogical study of four generations of this family revealed a descent pattern of inheritance. Anticipation--a characteristic phenomenon of the disease expressed in the occurrence of the disorder at earlier ages and in more severe forms in the successive generations--was also observed.