Clinical variability in KBG syndrome: report of three unrelated families.

The KBG syndrome is characterized by short stature, macrodontia, a specific combination of minor anomalies, developmental delay, and/or mental retardation. We reported on four patients from three unrelated families. The most frequent clinical findings were: atypical face, long/flat philtrum, thin upper lip, macrodontia, dental malposition, enamel hypoplasia, and cleft teeth. Skeletal anomalies such as cervical ribs and vertebral abnormalities were also noted. Hand anomalies were observed in three patients. Mental retardation and developmental delay were present in three of the four patients. There is wide clinical variability in the expression of this syndrome. The males are usually more severely affected then the females, suggesting possible X-linked inheritance in some cases.