How to counsel in osteopathia striata with cranial sclerosis

Osteopathia with cranial sclerosis (OS-CS) is an autosomal dominant condition, which is characterized by typical radiological changes of the skull and the long bones, in association with a wide variety of clinical symptoms. A family is reported with at least three affected individuals. One of them, a young women and her husband asked for a preconceptional advice, but the highly variable expressivity, as documented by this family, made it very difficult to counsel them properly.