Sibs with cleidocranial dysplasia born to normal parents: germ line mosaicism?

Cleidocranial dysplasia (CCD) is classically an autosomal dominant disorder. However, the possibility of an autosomal recessive form of CCD has been suggested based on a report of 2 consanguineous families, one with a single affected child, the second with affected sibs, born to normal parents. We present a family with sibs with CCD born to normal parents, and suggest germ line mosaicism as the more likely mechanism for this occurrence.