Multiple cranial nerves may be involved (nerves
V, VI, VII, IX, X, and XII can all be affected) and lead to orofacial
malformations, abnormalities of tongue coordination, swallowing (bulbar
muscle weakness), and drooling. Speech abnormalities are common. High risk
for corneal abrasions. Usually the affected individuals are mentally normal. However, there is a 10%
incidence of mild mental retardation. Occasionally peripheral neuropathy and
pectoral muscle deficiency. Abnormalities of ventilation (central
hypoventilation and idiopathic tachypnea) presumably result from brainstem
abnormalities. Craniofacial features include micrognathia, microstomia,
mandibular hypoplasia, tongue tethering, premaxillary overgrowth, and cleft
lip and palate. Strabismus is common. Congenital cardiac anomalies include
ventricular septal defect (VSD) and patent ductus arteriosus (PDA). Skeletal features are talipes
equinovarus (in up to 50%), arthrogryposis, and terminal limb defects. Cervical spine anomalies have
been described.