A male infant was born at the 36th week of gestation by cesarean section because of an intrauterine bradycardy. There was a 2nd degree a. v.-bloc postnatal. The heart rate was normal after the 5th day of life with a QT-interval of 150 percent resp. 120 percent after the 15th day. Additionally there were syndactylies of hands and feet. The infant suddenly died at the age of 5 months. Examination of the parents revealed a QT-interval of 115 percent as well as synostoses of the carpus in the father. These microsymptoms are very important for genetic counseling of the family. There is a recurrence risk of 50 percent for further children because a dominant trait is to be suggested.