This is a complex and highly variable hereditary disorder with manifestations throughout the body. Features such as the unusual facies and skull may be identifiable at birth. Most characteristics are not progressive.
Infants are usually 'floppy' at birth. Facial muscles seem to be paralyzed and, in particular, the eyes do not move normally. The eyelids droop and the openings slant downward. The skull can appear large or may be smaller than normal and have an abnormal shape.
The lower jaw is often underdeveloped and the tongue is abnormally large. Many infants have breathing and swallowing difficulties starting at birth. Failure to thrive and developmental delays are common although not always present. Intellectual disability is often present to some degree. Holes in the heart partitions are common. Clubfeet are found in many individuals along with a cleft palate. The brain often contains malformations involving critical structures.
This is an autosomal recessive disorder resulting from changes (mutations) in both members of a specific pair of genes. Parents are clinically normal but if both carry a single copy of the mutation, each of their children have a 25% risk of inheriting this condition.
An experienced pediatrician or neurologist might recognize this rare disease at birth or early infancy. It is important to recognize breathing and swallowing difficulties early so they can be addressed appropriately. Childhood development requires early intervention to maximize and stimulate neurological growth. Physical therapy could be beneficial also. Gastric feeding tubes may be required for proper nutrition. Surgery on eye muscles to improve motion in mild cases might be helpful but unlikely to restore full motility.
Intensive physical, nutritional, and emotional support is required throughout life in most individuals. The negative impact on longevity can be significant, especially for those with breathing problems who can be susceptible to recurrent lung infections.