We report the first family with a dominantly inherited mutation of the nebulin gene (NEB).

Impact: Our finding is the first instance of a plausible candidate high penetrance inherited mutation predisposing to NPC.

We describe the genetic findings, phenotypic variability, and recessive inheritance of an often dominantly inherited mutation as notable elements in their case.

The secondary mutation may involve a substantial loss of chromosomal material and thus lead to identification of the site of the inherited mutation.

We have studied three families with congenital onset, each with a dominantly inherited mutation in a C-terminal exon of the ryanodine receptor 1.