THROUGH the investigation of familial abnormalities, it is sometimes possible to demonstrate clear-cut modes of inheritance, thus defining further the mechanisms of human biology and aiding intelligent genetic counseling. In one such investigation a large family with an inherited congenital abnormality, the oralfacial-digital (OFD) syndrome, was described.1
The OFD syndrome is a multisystem condition in females, characterized by the occurrence of various clinical signs. These signs commonly include a typical pugnosed profile; pseudocleft upper lip; cleft tongue and tongue hamartomas; cleft or pseudocleft palate; multiple buccal frenula causing alveolar ridge clefts and malpositioning of teeth; short, stubby hands with webbing; extra digits of the feet; polycystic kidneys; and mental retardation.1-4
The several previous studies1,3-5 relating mental retardation to the OFD syndrome have not included desirable controls. One method by which to control some of the effects of cultural and environmental factors is to compare affected and