The facial features are considered to be distinctive, characterized by a broad, square face, prominent forehead, broad nasal bridge, and midface hypoplasia. These and other features appear more pronounced with age as in the size of the jaw which is underdeveloped in infancy and eventually becomes prognathic. Most patients have developmental delays, speech and motor deficits, cognitive impairments and behavioral abnormalities. Hypotonia, hyporeflexia, failure to thrive, lethargy, and feeding difficulties are common in infants. Older individuals have REM sleep disturbances with self-destructive behaviors, aggression, inattention, hyperactivity, and impulsivity. Short stature, hypodontia, brachydactyly, hearing loss, laryngeal anomalies, and peripheral neuropathy are common. Seizures are uncommon.
The behavioral profile of this syndrome can resemble that of autism spectrum disorders although symptoms of compulsivity are more mild.
A related developmental disorder known as Potacki-Lupski syndrome (610883) involving the same locus on chromosome 17 has a similar behavioral profile. Ocular and systemic malformations may be less severe though.