The Coffin-Siris syndrome: report of a family and further delineation.

The familial occurrence of the Coffin-Siris syndrome, combining a typical facial appearance with hypoplastic or absent fifth finger- or toenails, is reported. The full expression of the syndrome was present in two sisters, and partial clinical manifestations were present in their mentally borderline father. The relevant literature is reviewed, and the relation and confusion with other mental retardation syndromes, mainly the Coffin-Lowry syndrome, is discussed.