Treacher Collins syndrome produces a distinctive pattern of facial features that primarily affects the cheekbones, jaw, eyes, and ears. The severity varies widely, from cases so mild they go undiagnosed into adulthood to cases that require airway intervention at birth. Every person with the condition looks different, but the underlying pattern is consistent: the bones and soft tissues of the face, particularly in the lower and middle portions, are underdeveloped.
Cheekbones and Overall Facial Shape
The most defining feature is underdeveloped cheekbones. The zygomatic bones, which form the prominent ridge below and to the side of your eyes, are small or flattened. This gives the midface a sunken or flat appearance rather than the typical contour most people have. Because the cheekbones provide structural scaffolding for the face, their absence affects the overall facial shape in a way that’s often noticeable even from a distance.
In mild cases, the cheekbones are slightly smaller than average and may only be apparent on imaging. In more severe cases, the cheekbones are nearly absent, creating a dramatic change in facial proportions that makes the eyes and forehead appear more prominent by comparison.
Eyes and Eyelids
The eyes slant downward at the outer corners, a feature doctors call downward-slanting palpebral fissures. This is one of the most recognizable signs and is directly related to the underdeveloped cheekbones, which normally support the lower eye socket. Without that bony support, the outer corners of the eyes angle downward instead of sitting level or slightly upward.
Many people with Treacher Collins also have a notch or gap in the lower eyelids called an eyelid coloboma. This looks like a small wedge-shaped defect in the eyelid margin. Eyelashes along the lower lid are often sparse or missing entirely, particularly on the inner portion. These eyelid features can affect how well the eyes stay lubricated, since the lids may not close completely during blinking or sleep.
Jaw and Chin
The lower jaw is characteristically small and set further back than usual, a feature called micrognathia. This gives the chin a receding appearance and can make the face look narrow from the side. In some cases, the jaw is so underdeveloped that the tongue sits further back in the throat, partially blocking the airway. Obstructive sleep apnea is common as a result, and in severe cases, newborns may need immediate help breathing.
The small jaw also changes the way the upper and lower teeth line up. Many people with the condition have a significant overbite or open bite, where the upper and lower teeth don’t meet properly when the mouth is closed. This can affect chewing and speech.
Ear Shape and Hearing
The ears are one of the most visibly affected features. They range from slightly small and unusually shaped (grade 1 microtia) to a small peanut-shaped nub of tissue with no recognizable ear structure (grade 3, the most common form of microtia). In rare cases, the external ear is completely absent. Both ears are often affected, though one side is sometimes more severe than the other.
Beyond the visible differences, the ear canal is frequently narrow or completely absent. The tiny bones inside the middle ear that transmit sound may also be malformed or missing. This means most people with Treacher Collins have some degree of conductive hearing loss, where sound can’t travel efficiently from the outer ear to the inner ear. The inner ear itself usually works normally, which is why hearing aids or bone-anchored hearing devices are effective for many people with the condition.
Dental Differences
Because the jaw and surrounding bones are underdeveloped, dental problems are common and often noticeable. Teeth may come in crowded, misaligned, or rotated because there isn’t enough space in the jaw to accommodate them. Some teeth never develop at all. Others have enamel that appears cloudy or discolored, making them look different from typical teeth even when they do emerge. Upper molars sometimes erupt in unusual positions. These dental differences tend to compound the bite problems created by the small jaw, and orthodontic treatment is a common part of long-term care.
How Severity Varies
One of the most important things to understand about Treacher Collins syndrome is how dramatically the appearance varies from person to person, even within the same family carrying the same genetic mutation. At the mild end of the spectrum, a person might have slightly flat cheekbones, a subtle downward slant to the eyes, and small ears that are otherwise normally shaped. These individuals sometimes aren’t diagnosed until a more severely affected child is born in the family, prompting doctors to look more closely at the parents.
At the severe end, the facial bones are profoundly underdeveloped. The cheekbones may be nearly absent, the jaw extremely small, the ears reduced to small nubs, and the airway compromised enough to require surgical intervention in infancy. Most people fall somewhere between these extremes, with a combination of features that are clearly present but manageable with staged treatment over childhood and adolescence.
How Features Change With Age and Treatment
The facial features of Treacher Collins syndrome are present at birth and don’t resolve on their own, but they do change over time through both natural growth and surgical reconstruction. In infancy, the small jaw and airway concerns tend to dominate. Some babies need a procedure called mandibular distraction, where the jawbone is gradually lengthened over several weeks, to open the airway enough for safe breathing.
As children grow, the focus shifts to the cheekbones and eye sockets. Bone grafts can rebuild the cheekbone area, improving both appearance and the structural support around the eyes. Ear reconstruction, when desired, typically happens in later childhood, often using rib cartilage to build an ear framework that’s placed under the skin. Eyelid repair to close colobomas and protect the eyes is usually done earlier.
By adulthood, many people with Treacher Collins have undergone multiple reconstructive procedures that significantly change their appearance compared to how they looked as young children. The underlying bone structure remains smaller than average, but modern craniofacial surgery can restore much of the facial contour, improve jaw function, and create recognizable ear shapes. The condition affects roughly 1 in 50,000 births, and because treatment has advanced considerably in recent decades, adults living with Treacher Collins today often look quite different from the textbook photos that come up in a search.