A single 5 generation family has been reported with this inherited nonprogressive condition.
Affected members of the reported family with this nonprogressive condition have a reduced gag reflex and anatomical anomalies of the upper throat resulting in difficulty swallowing. Facial muscles are immobile leading to an expressionless face. Speech is commonly nasal in quality. The upper eyelids appear to droop (ptosis) and it is common for patients to tilt their head back to see under the lids through the nearly closed openings.
There are no other neurologic or skeletal signs. Intellectual abilities are normal.
Based on the transmission pattern in the single reported family, this condition is inherited as an autosomal dominant disorder. A gene mutation has been found that is responsible. Parents with this disorder can transmit it directly to their offspring with a 50% probability.
The immobile face is present at birth and the droopy eyelids and swallowing difficulties may also be apparent at that time. The diminished gag reflex can result in regurgitation and serious lung inflammation (pneumonitis) is a risk. Surgical repairs of the upper throat (pharynx) might improve the nasalized speech and swallowing problems. Lid surgery to lift the drooping upper eyelids can allow for a more normal head position and improved field of vision.
There is no information available on longevity.