Most common features are in bold text
General:
• Global developmental delay (100% of cases)
• Obesity (53% of cases)
Neurological:
• Intellectual disability
• Hypotonia (100% of cases)
• Dysautonomia
• Epilepsy (50% of cases)
• MRI abnormalities (53.8% of cases)
o Brain dysmyelination
o Brain atrophy
Respiratory:
• Hypoventilation (65% of cases)
• Sleep apnea
• Recurrent pneumonia
Abdomen:
• Gastrointestinal reflux disease
• Constipation
Skeletal:
• Scoliosis
Head and Neck:
• Variable mild facial dysmorphism
• Abnormalities of the eye, including nystagmus, poor vision, and abnormal eye movements
P4HTM