PACS1 syndrome

PACS1 syndrome is a condition in which all affected individuals have intellectual disability, speech and language problems, and a distinct facial appearance. Many affected individuals have additional neurological, behavioral, and health problems.

In PACS1 syndrome, intellectual disability typically ranges from mild to moderate. Individuals with this condition also have problems with producing speech (expressive language). Speech development ranges from limited language to few words or no speech.

Individuals with PACS1 syndrome have a distinct facial appearance. Facial features include thick and highly arched eyebrows, long eyelashes, widely set eyes (hypertelorism), outside corners of the eyes that point downward (downslanting palpebral fissures), droopy eyelids (ptosis), a rounded nasal tip, a wide mouth with corners that point downward, a thin upper lip, a smooth area between the nose and upper lip (philtrum), widely spaced teeth, and ears that are low-set with fewer folds and grooves than normal (described as "simple"). Abnormalities of other body systems can also occur, such as malformations of the heart, brain, eyes, or other organs. Males may have undescended testes (cryptorchidism).

Children with PACS1 syndrome often have problems learning to eat solid food and prefer soft foods. When given solid foods, affected children often swallow without chewing. These food issues tend to persist throughout life. Some affected individuals experience a backflow of stomach acids into the esophagus (gastroesophageal reflux).

Additional neurological problems can occur in PACS1 syndrome. Some affected individuals have features of autism spectrum disorder, which is characterized by impaired communication and social interaction. Attention-deficit/hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), self-injury, or frustration leading to tantrums can also occur. Most individuals with PACS1 syndrome have seizures that vary in type and age of onset. Some people with PACS1 syndrome have weak muscle tone (hypotonia). Individuals with this condition are often delayed in walking, with some developing an unsteady walking style (gait). Rarely, affected individuals have frequent falls and gradually lose their ability to walk in late childhood, requiring wheelchair assistance.