Failure of both membranous and long bones to grow properly lead to a variety of abnormalities such as craniosynostosis, hypomelia, syndactyly, oligodactyly, malar hypoplasia, short neck, micrognathia, and cleft lip and palate. The long bones of the limbs may be underdeveloped or even absent. Contractures of elbow, knee, and ankle joints are common as are digital anomalies. Low birth weight and slow postnatal growth rates are usually result in short stature. The hair is often sparse and light-colored.
Mental development is impaired and some children are diagnosed to have mental retardation. Cardiac defects are common. Facial hemangiomas are often present as are septal defects and sometimes a patent ductus arteriosus. External genitalia in both sexes appear enlarged. The kidneys may be polycystic or horseshoe-shaped.