People with Möbius syndrome have normal intelligence, although their lack of facial expression is sometimes incorrectly taken to be due to dullness or unfriendliness.

[2] People with Möbius syndrome are born with facial paralysis and the inability to move their eyes laterally.

[7] Due to the importance of facial expression and smiling in social interaction, the inability to form either can lead to individuals with Möbius being perceived as unhappy, unfriendly or uninterested in conversations.

[8] Individuals who are familiar with Möbius patients such as family or friends can recognize other signals of emotion such as body language, to the point that they sometimes report forgetting that the person has facial paralysis.

[9] People with Möbius syndrome are often adept at compensating for a lack of expression by using body language, posture, and vocal tone to convey emotion.

It is thought to result from a vascular disruption (temporary loss of blood flow) in the brain during prenatal development.

Some maternal trauma may result in impaired or interrupted blood flow (ischemia) or lack of oxygen (hypoxia) to a developing fetus.

The palate may have a groove (this may be partially due to intubation early on if it is for an extended period of time) or may be cleft (incompletely formed).

Interceptive orthodontic treatment can be initiated at this stage of development to help with crowding or to help relate the upper and lower jaws.

Appliances that expand the upper arch tend to bring the front teeth back into a more-normal position.

If they have difficulty nursing, infants may require feeding tubes or special bottles to maintain sufficient nutrition.

Physical, occupational, and speech therapy can improve motor skills and coordination and can lead to better control of speaking and eating abilities.

Surgery can correct crossed eyes, protect the cornea via tarsorraphy, and improve limb and jaw deformities.

[18][19] Although its rarity often leads to late diagnosis, infants with this disorder can be identified at birth by a "mask-like" lack of expression that is detectable during crying or laughing and by an inability to suck while nursing because of paresis (palsy) of the sixth and seventh cranial nerves.