Familial, isolated, complete right bundle-branch block.

An electrocardiographic study of the families of two children with isolated complete right bundle-branch block is presented. Several cases of classical complete right bundle-branch block were disclosed (17/69 and 3/22 respectively) in three generations of the two families. Personal interviews and parish registers showed that the two families were related, being descendants 8 generations back from a glass-blower who has emigrated to Sweden in the eighteenth century. It is concluded that complete right bundle-branch block can be an autosomal, genetic anomaly which is inherited dominantly but with reduced penetrance and/or expressivity.