What is Mandibulofacial Dysostosis (Treacher Collins)?
Treacher Collins syndrome, also known as mandibulofacial dysostosis, is a rare birth condition that affects the development of the face and head. This condition can show up differently in each person. More than half of cases occur due to random genetic changes, although it can also run in families. When it’s inherited, it usually follows what scientists call an ‘autosomal dominant’ pattern, which means it can be passed on by just one parent. Three genes, TCOF1, POLR1C, and POLR1D, are often involved when this happens.
Common signs of Treacher Collins syndrome include eyes that slant downwards, a small lower jaw and cheekbones (sometimes appearing as special types of clefts called Tessier clefts 6, 7, 8), deformities in the lower eyelids, malformed outer ears (or even small-sized ears), and issues with mid-ear development leading to hearing loss. Usually, these features are symmetrical and apparent on both sides of the face. Studies have connected Treacher Collins syndrome to improper development of certain structures in the embryo, known as the first and the second branchial arches.
Initially, this condition was described by different scientists such as Berry in 1889 and Treacher Collins in 1900, hence the names Berry’s syndrome and Franceschetti-Zwahlen-Klein syndrome popped up in some old researches. However, the name Treacher Collins syndrome is more commonly used today as Collins provided a detailed description of the condition. Franceschetti and Klein coined the term mandibulofacial dysostosis, which is often used nowadays as most modern medical literature tries to avoid eponyms (names based on people).
The abnormalities in face and head structure seen in Treacher Collins syndrome can cause issues with breathing, speaking, hearing, and eating. Care for individuals with this condition is best coordinated by a team of various healthcare professionals, who can manage different aspects of their wellbeing.
What Causes Mandibulofacial Dysostosis (Treacher Collins)?
Treacher Collins syndrome (TCS) is a condition that results from genetic mutations, and its effects can vary greatly from person to person. It most commonly follows an autosomal dominant pattern of inheritance, meaning it gets passed down from parents to children, but it can also be autosomal recessive, which is less common. The majority of cases are spontaneous, meaning there isn’t a family history of the syndrome. Around 60% of individuals with TCS have no family history of it and are a result of a spontaneous or ‘de novo’ mutation.
The syndrome has been associated with specific parts of human DNA, specifically the region known as 5q32 on chromosome 5. If a person has the dominant form of TCS, each of their children has a 50% chance of getting the disease-causing mutation. If the person has the recessive form of TCS, the parents of a child with the syndrome are carriers of a TCS-related mutation, but they typically don’t show symptoms of the disease themselves. In this case, each sibling of the affected person has a 25% chance of also having TCS, a 50% chance of being a carrier but without any symptoms, and a 25% chance of not having TCS or carrying the mutation.
Not everyone with TCS shows the same symptoms, so it can sometimes go unnoticed in people with milder forms of the disease. But in severe cases, it can cause serious health problems like difficulties with breathing due to alterations in facial structure.
Once a mutation related to TCS has been found in a family, doctors can offer genetic tests before pregnancy or during pregnancy to see if the baby will have the disease. It can also offer the family an idea of the likelihood of having another child with the disease. Doctors strongly recommend that those affected by TCS and their families should seek advice from a genetic counselor.
Risk Factors and Frequency for Mandibulofacial Dysostosis (Treacher Collins)
Treacher Collins syndrome is a condition that occurs in around 1 in 25,000 to 1 in 70,000 babies born, with the most common estimate being 1 in 50,000. It doesn’t favor any specific gender or race. The form and severity of the condition at birth generally stays the same and doesn’t progress or get worse.
Signs and Symptoms of Mandibulofacial Dysostosis (Treacher Collins)
Treacher Collins syndrome is a condition characterized by specific physical features. These include:
- Eyes angled downwards, with shallow lower lids and outside corners, a large space between the eyes, partial or complete lack of eyelashes and sometimes even issues with vision.
- Underdeveloped cheekbones and a small lower jaw which can cause problems like sleep apnea
- Ear abnormalities, usually related to the external part of the ear and oftentimes associated with issues of the middle ear. This can lead to problems with hearing in most cases.
- Other less common signs can include irregularities of the salivary glands leading to dry mucous membranes, cleft palate or lip, narrowing or blocking of the nasal airway passages, anomalies of the nose and palate, and rare heart irregularities.
Despite these physical abnormalities, people with Treacher Collins syndrome typically have a normal intellect. Cases of disability or delayed motor development are extremely rare but notable.
Testing for Mandibulofacial Dysostosis (Treacher Collins)
Treacher Collins Syndrome, or TCS, affects everyone differently, so it’s important to have a health care team that can perform a thorough checks tailored the individual’s specific needs. The examinations usually focus on the following areas:
1. Eye check-ups: This includes looking at the eyelids and testing the clarity or sharpness of vision (visual acuity).
2. Hearing tests: This is very important as most people with TCS experience hearing problems. Early treatment can make sure that language development and hearing correction can begin as soon as possible.
3. An examination of the upper airway: This is needed because some people with small or set-back lower jaws (micrognathia and retrognathia) might also have problems with sleep apnea, where the breathing stops and starts whilst sleeping.
A diagnosis of TCS is often confirmed via a blood test, where the healthcare team extracts DNA from family members and the person suspected of having TCS. The blood test looks for specific genetic changes that are known to cause TCS. When the genetic change is found in a person, the same test can be used to check if an unborn baby (foetus) or in-vitro fertilization (IVF) embryo has TCS. This particular test is usually only offered to persons with a family history of TCS or when the baby shows certain signs of the syndrome during ultrasound examination like small jaw (micrognathia) and small ear (microtia).
Around 96% of TCS diagnoses are confirmed by genetic tests which detect changes in the TCOF1 or POLR1D genes in an autosomal dominant pattern (one copy of the gene change is enough for the person to have the syndrome) or in both copies of the POLR1C or POLR1D genes in an autosomal recessive pattern for the syndrome (two copies of the gene change are required for the person to have the syndrome). For the remaining, approximately 4% of patients are diagnosed based on physical characteristics when genetic testing was not conducted or didn’t reveal any specific genetic changes.
In the first six months of life, a craniofacial (related to the bones in the face and head) CT scan is usually done to determine the extent of abnormal bone structure. This CT scan can reveal if the cheekbone arches (zygomatic arch) are underdeveloped (hypoplastic) or missing (aplastic), and if the lower jaw is set back from the face (retrognathia). Although X-rays can often show similar signs, they are rarely used now due to the widespread availability of CT scans.
If the doctors are concerned about sleep apnea, they may recommend a sleep study (polysomnography) and a thorough check-up of the ear, nose, and throat to determine the level of obstruction in the upper airway.
Treatment Options for Mandibulofacial Dysostosis (Treacher Collins)
Treacher Collins syndrome is a condition that doesn’t currently have a cure, but it can be managed through treatments specifically tailored to the patient’s needs. This usually requires a team of various specialists and largely depends on how the patient grows, their unique symptoms, and their mental health needs. Some may not even need surgery.
One common issue these patients face is Obstructive Sleep Apnea. This occurs when there is blockage in the upper airway, sometimes caused by problems in the facial bones or due to the position of the tongue. Recognising the signs of sleep apnea is an important early step in managing the condition. For newborns with severe airway obstruction, several measures can be explored, including special ways of positioning the baby during sleep and, in some cases, surgery. Tracheostomy, a procedure where a hole is made in the neck to assist breathing, may be needed in 12 to 41% of cases but its use is usually a last resort given that it can interfere with speech and result in scar tissue.
Another issue that Treacher Collins syndrome patients might face is difficulty eating. This is particularly true for those with mandibular hypoplasia, a condition where the lower jaw is underdeveloped. In these cases, a gastric tube may be necessary for feeding. Dental problems created as a result of this condition can also limit food options and make brushing teeth hard.
Speech delays can also be an issue due to a variety of potential reasons. For instance, tracheostomies, the underdevelopment of the lower jaw, and differences in dental alignment can all potentially affect speech development, while abnormal nasal passages can affect speech quality. Early intervention measures such as hearing and speech therapy can help manage these issues.
Ear malformations and hearing impairment are also common in Treacher Collins syndrome, so getting early evaluations by a children’s ear, nose, and throat specialist is crucial. The use of hearing aids and speech therapy can be very helpful for these cases. Surgeries to repair the outer ear are usually not done until the child is between six and nine years old, with the aim of improving the appearance rather than hearing.
Eyes and vision may also be affected in Treacher Collins syndrome, with measures like orbital dystopia correction (fixing the position of the eyes) and lateral canthopexies (surgical modification of the corners of the eye) rarely needed. Most individuals with this syndrome tend to have normal or near-normal vision, despite the abnormal positioning of their eyes. In severe cases where the eyelids don’t fully cover the eyes, a procedure to lengthen the lids may be necessary.
Potential facial deformities such as mandibular (jaw) and malar (cheekbone) hypoplasia are typically addressed surgically depending on the severity. Timing for such surgeries is typically determined by the patient’s growth, usually in their late teens. Similarly, any required renovations to the nose tend to take place after all jaw procedures have been completed, typically after the age of 17.
Repairing a cleft (gap) in the palate, a common issue with Treacher Collins syndrome, usually happens at around one year of age. It’s important to check if closing the gap would affect the child’s breathing, to avoid complications after the operation.
Last, but definitely not least, it’s crucial to prioritize the psychological well-being of individuals dealing with Treacher Collins syndrome. Its physical manifestations may impact self-confidence and day-to-day life. Regular mental health check-ups with a psychologist or psychiatrist should be part of the treatment plan to ensure holistic care for these patients.
What else can Mandibulofacial Dysostosis (Treacher Collins) be?
Doctors may suspect a number of different conditions when diagnosing Treacher Collins syndrome. The presence of symmetric and bilateral hearing loss is often seen in Treacher Collins syndrome, making it different from some other conditions. This highlights how important a thorough hearing evaluation is when considering syndromic diagnoses.
- Goldenhar syndrome, also known as vertebral oculo-auricular dysplasia, has similar facial abnormalities to Treacher Collins syndrome. However, Goldenhar syndrome is usually one-sided and asymmetrical, while Treacher Collins is typically symmetrical. Additionally, Goldenhar syndrome often includes spinal abnormalities and tumors on the eye, which do not appear in Treacher Collins syndrome.
- Nager syndrome has facial features somewhat like Treacher Collins syndrome. However, in Nager syndrome, there are limb defects that are located on the thumb side of the hand, whereas there are none linked with Treacher Collins syndrome.
- Miller syndrome also has facial features similar to Treacher Collins syndrome. But in this case, the limb defects occur towards the little finger side, while Treacher Collins has no associated limb defects.
- Non-syndromic congenital mandibular hypoplasia is a rare condition involving an underdeveloped lower jaw. This isn’t associated with any syndrome. Following jaw surgery, these patient’s jaws tend to return to their pre-surgical shape, unlike the jaws of patients with Treacher Collins syndrome which tend to retain the new shape post-surgery.
Proper identification of these conditions is essential in determining appropriate treatment and care.
What to expect with Mandibulofacial Dysostosis (Treacher Collins)
People with Treacher Collins syndrome, if properly cared for, can expect to live as long as anyone else. A priority is ensuring their psychological wellbeing early on. This can be influenced by factors like how unafraid they are of being negatively judged on their appearance, their contentment with their own appearance, and their level of self-esteem. These are strong indicators of lasting mental health.
Interestingly, the severity of the physical abnormality doesn’t significantly impact their psychological wellbeing. However, early intervention to address hearing problems is incredibly important. This helps them integrate into regular schooling and social activities with their peers, since intellectually, they’re usually on the same level as everyone else.
It’s worth noting that people born with craniofacial conditions are less likely to have a partner or children. They also tend to internalize, or keep to themselves, their behavior problems.
Possible Complications When Diagnosed with Mandibulofacial Dysostosis (Treacher Collins)
People with Treacher Collins syndrome can face various health issues that can disrupt their quality of life. These problems can include:
- Sleep disruption due to breathing problems (obstructive sleep apnea)
- Delayed speech development
- Issues with hearing
- Difficulties related to eating
- Problems with vision
- Mental health challenges (psychological sequelae)
Additionally, they may also face risks associated with surgery which can cause illness or even death.
Preventing Mandibulofacial Dysostosis (Treacher Collins)
Treacher Collins syndrome is a condition that varies a lot from person to person, both in terms of its causes, which are genetic, and how it shows up, which can be seen physically. This makes genetic counseling very important for better understanding. There is no cure for this condition at present, but treatments can be geared toward dealing with specific symptoms and needs of each person.
It’s best to manage this condition using a team of healthcare professionals, each with their own areas of expertise. The visible irregularities associated with Treacher Collins syndrome are typically addressed in multiple stages. This correction process considers factors like facial growth patterns, the functioning of the facial features, and the psychological needs of the patient.
The good news is that with the right management, individuals living with Treacher Collins syndrome can expect to live just as long as the average person.
