In some cases, the physical signs of Treacher Collins syndrome are so mild they can only be detected by an expert. In other cases, these signs may be obvious. For example, the nose, throat and jaw tend to be underdeveloped in patients with Treacher Collins syndrome, while the mouth is usually enlarged.

Ear abnormalities are common in patients with Treacher Collins syndrome. The ears may be small, low-set or almost completely absent. Other ear abnormalities include absence of the external auditory canal, prominent outer ears, the presence of ear tags (extra bits of skin in front of the ear) and preauricular pits (little holes in front of the opening of the external ear).

A cleft palate is also associated with Treacher Collins syndrome in 33 percent of cases. This occurs when the roof of the mouth (palate) is either underdeveloped or split.

Drooping eyelids are another common feature of Treacher Collins syndrome. These often give a child a saddened appearance. In some cases, a small notch is missing from the lower eyelid, a condition known as coloboma. The eye may be abnormally shaped and there may be few eyelashes on the lower eyelid.

Other physical signs of Treacher Collins syndrome include:

• Tendency toward dry eyes, which can lead to infection
• Flat cheekbones
• Scalp hair that extends to the cheeks
• Abnormally small or absent thumbs

Breathing problems often accompany Treacher Collins syndrome because airway space is reduced due to small, undeveloped jaws that position the tongue farther back in the mouth. Colds and infections can exacerbate breathing problems due to congestion and swelling of tissue lining the airway.   

Conductive hearing loss is also frequently associated with Treacher Collins syndrome. "Conductive" means the impairment is a result of abnormalities in the structure of the outer auditory canal and middle ear bones. While the degree of hearing loss may vary, there is usually about a 40 percent loss in each ear that does not diminish to the level of deafness. In most cases, hearing loss affects both ears and is significant enough to hinder a child’s ability to hear the human voice.