Treacher Collins syndrome

Treacher Collins syndrome is a genetic disorder that affects the growth and development of the head. It prevents the skull, cheek and jawbones from developing properly, causing facial anomalies and hearing loss.

About one child in every 50,000 is affected. Problems range in severity from mild to very severe, and in most cases the child’s intelligence is unaffected. The syndrome is either inherited or caused by a new change in a gene at the time of conception.

There is no cure, but skull and face (craniofacial) surgery can improve speech and reduce some of the more severe craniofacial anomalies. Treacher Collins syndrome is also known as mandibulofacial dysostosis or Franceschetti syndrome.

Symptoms#

Signs and symptoms range from barely noticeable to severe and disabling. Features of a person with Treacher Collins syndrome may include:

• cleft palate
• a small jawbone (micrognathia)
• a disproportionately large mouth (macrostomia)
• small or absent cheekbones
• a large and pointed nose
• droopy, misshapen eyes with notched lower lids
• absent lower eyelashes
• an absent floor of the eye sockets
• overgrowth of scalp hair onto the cheeks
• low-set, misshapen, small or absent ears
• deformities of the ear canal
• conductive hearing loss or deafness, caused by malformations of inner ear structures

Cause#

A change in the gene TCOF1 causes up to 93 per cent of cases of Treacher Collins syndrome. This gene, located on chromosome 5, is responsible for facial development. Another two per cent of cases are thought to be caused by changes in the genes POLR1C and POLR1D.

In about half of all cases, the gene change occurs for the first time at conception, with no previous family history. In other cases, the altered gene is inherited as an autosomal dominant trait. This means the child inherits the affected gene from a parent who has Treacher Collins syndrome, along with an unaffected copy of the gene from their other parent.

Exactly how the gene changes cause facial anomalies is not known. They are thought to cause cell death (apoptosis) of facial bone, cartilage and soft tissue during weeks three to eight of fetal development.

Pattern of inheritance#

An affected parent has a 50 per cent chance (one in two) of passing the affected gene on to each child they have. This is a chance event and cannot be altered. The severity of facial anomalies in a child who inherits the altered gene cannot be predicted.

Complications#

Complications depend on the severity of the condition and may include:

• feeding problems – a cleft palate can prevent a baby from suckling and swallowing
• breathing problems – a small jaw and average-sized tongue can interfere with breathing and lead to sleep apnoea; a tracheostomy (a surgical opening in the windpipe) may be needed in severe cases
• speech problems – may be caused by a cleft palate, conductive hearing loss or both
• learning problems – may be caused by hearing loss or deafness; the syndrome itself generally does not affect a child’s intelligence
• dry eye syndrome – may occur when there are not enough tears to keep the eyes moist and comfortable, and can lead to recurrent eye infections
• psychological problems – such as low self-esteem and depression caused by social stigma

Diagnosis#

Tests used to diagnose Treacher Collins syndrome may include a physical examination and a review of medical history. Genetic testing is also available but is often not necessary, as the diagnosis can usually be made on clinical features alone.

Treatment#

Treatment depends on the severity of the condition and may include:

• genetic counselling – for the individual or the whole family, depending on whether the condition was inherited
• hearing aids – usually helpful for conductive hearing loss
• dental work – including orthodontic work to help correct the child’s bite
• speech therapy – to improve communication skills; speech pathologists also help people who have trouble swallowing food or drink
• surgery – a number of operations can improve function and appearance

Surgery#

Depending on the severity of the craniofacial anomalies, surgical options may include:

• reconstruction of the lower eyelids
• closure of a cleft palate
• repair of absent facial bones, including the cheekbone and lower eye socket
• ear reconstruction
• repositioning of the lower jaw (orthognathic surgery)
• rhinoplasty to improve the appearance of the nose

The timing of these operations depends on the child’s age and stage of development. For example, eye surgery may be performed during infancy, ear reconstruction between the ages of five and seven years, and facial surgery after adolescence, once the face has stopped growing. Generally, reconstructive surgery has good results and helps the person to have a good quality of life.

Genetic counselling#

If your child has been diagnosed with Treacher Collins syndrome, or if it runs in your family, it may help to speak with a genetic counsellor. Genetic counsellors are health professionals qualified in both counselling and genetics.

As well as providing emotional support, they can help you understand Treacher Collins syndrome and what causes it, how it is inherited, and what a diagnosis means for your child’s health and development and for your family. They are trained to provide information and support that is sensitive to your family circumstances, culture and beliefs.

If the syndrome runs in your family, a genetic counsellor can explain what genetic testing options are available to you and other family members. You may choose to see one if you are planning a family, to understand your risk of passing the condition on to your child, or to arrange prenatal tests.

Key points#

• Treacher Collins syndrome prevents the skull, cheek and jawbones from developing properly, causing facial anomalies and hearing loss
• it is either inherited or caused by a new change in a gene at the time of conception
• signs and symptoms range from barely noticeable to severe and disabling
• a change in the gene TCOF1 causes up to 93 per cent of cases
• in other cases, the altered gene is inherited as an autosomal dominant trait

Where to get help#