Treacher-Collins Syndrome | |
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Other names | Treacher Collins–Franceschetti syndrome, [1] mandibulofacial dysostosis, [2] Franceschetti-Zwalen-Klein syndrome [3] |
Child with Treacher Collins syndrome [4] | |
Specialty | Medical genetics |
Symptoms | Deformities of the ears, eyes, cheekbones [5] |
Complications | Breathing problems, problems seeing, hearing loss [5] |
Causes | Genetic [5] |
Diagnostic method | Based on symptoms, X-rays, genetic testing [3] |
Differential diagnosis | Nager syndrome, Miller syndrome, hemifacial microsomia [3] |
Treatment | Reconstructive surgery, hearing aids, speech therapy [6] |
Prognosis | Generally normal life expectancy [6] |
Frequency | 1 in 50,000 people [5] |
Treacher Collins syndrome (TCS) is a genetic disorder characterized by deformities of the ears, eyes, cheekbones, and chin. [5] The degree to which a person is affected, however, may vary from mild to severe. [5] Complications may include breathing problems, problems seeing, cleft palate, and hearing loss. [5] Those affected generally have normal intelligence. [5]
TCS is usually autosomal dominant. [5] More than half the time it occurs as a result of a new mutation rather than being inherited. [5] The involved genes may include TCOF1 , POLR1C , or POLR1D . [5] Diagnosis is generally suspected based on symptoms and X-rays, and potentially confirmation by genetic testing. [3]
Treacher Collins syndrome is not curable. [6] Symptoms may be managed with reconstructive surgery, hearing aids, speech therapy, and other assistive devices. [6] Life expectancy is generally normal. [6] TCS occurs in about one in 50,000 people. [5] The syndrome is named after Edward Treacher Collins, an English surgeon and ophthalmologist, who described its essential traits in 1900. [7] [8]
Symptoms in people with Treacher Collins syndrome vary. Some individuals are so mildly affected that they remain undiagnosed, while others have moderate to severe facial involvement and life-threatening airway compromise. [9] Most of the features of TCS are symmetrical and are already recognizable at birth. [3]
The most common symptom of Treacher Collins syndrome is underdevelopment of the lower jaw and underdevelopment of the zygomatic bone. This can be accompanied by the tongue being retracted. The small mandible can result in a poor occlusion of the teeth or in more severe cases, trouble breathing or swallowing. The respiratory system of a child with Treacher Collins syndrome is the primary concern at birth, with other issues only addressed once respiratory function has been stabilized. [10] Underdevelopment of the zygomatic bone gives the cheeks a sunken appearance. [11] [12]
The external ear is sometimes small, rotated, malformed, or absent entirely in people with TCS. Symmetric, bilateral narrowing or absence of the external ear canal, is also described. [12] [13] In most cases, the bones of the middle ear and the middle ear cavity are misshapen. Inner ear malformations are rarely described. As a result of these abnormalities, a majority of the individuals with TCS have conductive hearing loss. [12] [14]
Most affected people also experience eye problems, including coloboma (notches) in the lower eyelids, partial or complete absence of eyelashes on the lower lid, downward angled eyelids, drooping of upper and lower eyelids, and narrowing of the tear ducts. Vision loss can occur and is associated with strabismus, refractive errors, and anisometropia. It can also be caused by severely dry eyes, a consequence of lower eyelid abnormalities and frequent eye infections. [12] [13] [15] [16]
Although an abnormally shaped skull is not distinctive for Treacher Collins syndrome, brachycephaly with bitemporal narrowing is sometimes observed. [13] Cleft palate is also common. [12]
Dental anomalies are seen in 60% of affected people, including tooth agenesis (33%), discoloration (enamel opacities) (20%), malplacement of the maxillary first molars (13%), and wide spacing of the teeth. In some cases, dental anomalies in combination with mandible hypoplasia result in a malocclusion. This can lead to problems with food intake and the ability to close the mouth. [12]
Less common features of TCS may add to an affected person's breathing problems, including sleep apnea. Choanal atresia or stenosis is a narrowing or absence of the choanae, the internal opening of the nasal passages, which may also be observed. Underdevelopment of the pharynx can also narrow the airway. [12]
Features related to TCS that are seen less frequently include nasal deformities, high-arched palate, macrostomia, preauricular hair displacement, cleft palate, hypertelorism, notched upper eyelid, and congenital heart defects. [11] [12] [16]
Although facial deformity is often associated with developmental delay and intellectual disability, more than 95% of people affected with TCS have normal intelligence. [12] The psychological and social problems associated with facial deformity can affect quality of life in individuals with TCS.
Mutations in TCOF1 , POLR1C , or POLR1D genes can cause Treacher Collins syndrome. [17] TCOF1 gene mutations are the most common cause of the disorder, with POLR1C and POLR1D gene mutations causing an additional 2% of cases. In individuals without an identified mutation in one of these genes, the genetic cause of the condition is unknown. The TCOF1, POLR1C, and POLR1D genes code for proteins which play important roles in the early development of bones and other tissues of the face. Mutations in these genes reduce the production of rRNA, which may trigger the self-destruction (apoptosis) of certain cells involved in the development of facial bones and tissues. It is unclear why the effects of a reduction in rRNA are limited to facial development. Mutations in TCOF1 and POLR1D cause the autosomal dominant form of Treacher Collins, and mutations in POLR1C cause the autosomal recessive form. [12]
TCOF1 is the primary gene associated with TCS, a mutation in this gene being found in 90–95% of the individuals with TCS. [11] [18] However, in some individuals with typical symptoms of TCS, mutations in TCOF1 have not been found. [19] Investigation of the DNA has resulted in the identification of the kind of mutations found in TCOF1. The majority of mutations are small deletions or insertions, though splice site and missense mutations also have been identified. [11] [20] [21] [22]
Mutation analysis has unveiled more than 100 disease-causing mutations in TCOF1, which are mostly family-specific mutations. The only recurrent mutation accounts for about 17% of the cases. [23]
TCOF1 is found on the 5th chromosome in the 5q32 region. It codes for a relatively simple nucleolar protein called treacle, that is thought to be involved in ribosome assembly. [18] Mutations in TCOF1 lead to haploinsufficiency of the treacle protein. [24] Haploinsufficiency occurs when a diploid organism has only one functional copy of a gene, because the other copy is inactivated by a mutation. The one normal copy of the gene does not produce enough protein, causing disease. Haploinsufficiency of the treacle protein leads to a depletion of the neural crest cell precursor, which leads to a reduced number of crest cells migrating to the first and second pharyngeal arches. These cells play an important role in the development of the craniofacial appearance, and loss of one copy of treacle affects the cells' ability to form the bones and tissues of the face. [12] [20] [25]
POLR1C and POLR1D mutations are responsible for a minority of cases of Treacher Collins. POLR1C is found on chromosome 6 at position 6q21.2 and POLR1D is found on chromosome 13 at position 13q12.2. Those genes code for a protein subunits shared between RNA polymerase I and III. Both of these polymerases are important for ribosome biogenesis. [12]
TCS is inherited in an autosomal dominant manner and the penetrance of the affected gene is almost complete. [26] Some recent investigations, though, described some rare cases in which the penetrance in TCS was not complete. Causes may be a variable expressivity, an incomplete penetrance [27] or germline mosaicism. [28] Only 40% of the mutations are inherited. The remaining 60% are a result of a de novo mutation, where a child has a new mutation in the responsible gene and did not inherit it from either parent. [12] [29] In the outcome of the disease, inter- and intrafamilial variability occurs. This suggests that when an affected child is born, it is important to investigate the parents to determine whether the affected gene is present, because the parent could have a mild form of the disease that has not been diagnosed. In this case, the risk of having another affected child is 50%. If the parents do not have the affected gene, the recurrence risk appears to be low. [26] In following generations, the severity of the clinical symptoms increases. [21]
Mutations in the main genes responsible for TCS can be detected with chorionic villus sampling or amniocentesis. Rare mutations may not be detected by these methods. Ultrasonography can be used to detect craniofacial abnormalities later in pregnancy, but may not detect milder cases. [12]
TCS is often first suspected with characteristic symptoms observed during a physical exam. However, the clinical presentation of TCS can resemble other diseases, making diagnosis difficult. [30] The OMENS classification was developed as a comprehensive and stage-based approach to differentiate the diseases. This acronym describes five distinct dysmorphic manifestations, namely orbital asymmetry, mandibular hypoplasia, auricular deformity, nerve development, and soft-tissue disease. [31]
Orbital symmetry
Mandible
Ear
Facial nerve
Soft tissue
A few techniques are used to confirm the diagnosis in TCS. [30] [32]
An orthopantomogram (OPG) is a panoramic dental X-ray of the upper and lower jaw. It shows a two-dimensional image from ear to ear. Particularly, OPG facilitates an accurate postoperative follow-up and monitoring of bone growth under a mono- or double-distractor treatment. Thereby, some TCS features could be seen on OPG, but better techniques are used to include the whole spectrum of TCS abnormalities instead of showing only the jaw abnormalities. [30]
Another method of radiographic evaluation is taking an X-ray image of the whole head. The lateral cephalometric radiograph in TCS shows hypoplasia of the facial bones, like the malar bone, mandible, and the mastoid. [30]
Finally, occipitomental radiographs are used to detect hypoplasia or discontinuity of the zygomatic arch. [32]
A temporal-bone CT using thin slices makes it possible to diagnose the degree of stenosis and atresia of the external auditory canal, the status of the middle ear cavity, the absent or dysplastic and rudimentary ossicles, or inner ear abnormalities such as a deficient cochlea. Two- and three-dimensional CT reconstructions with VRT and bone and skin-surfacing are helpful for more accurate staging and the three-dimensional planning of mandibular and external ear reconstructive surgery.[ citation needed ]
Other diseases have similar characteristics to Treacher Collins syndrome. In the differential diagnosis, one should consider the acrofacial dysostoses. The facial appearance resembles that of Treacher Collins syndrome, but additional limb abnormalities occur in those persons. Examples of these diseases are Nager syndrome and Miller syndrome. [3]
The oculoauriculovertebral spectrum should also be considered in the differential diagnosis. An example is hemifacial microsomia, which primarily affects development of the ear, mouth, and mandible. This anomaly may occur bilaterally. Another disease which belongs to this spectrum is Goldenhar syndrome, which includes vertebral abnormalities, epibulbar dermoids and facial deformities. [33]
The treatment of individuals with TCS may involve the intervention of professionals from multiple disciplines. The primary concerns are breathing and feeding, as a consequence of the hypoplasia of the mandibula and the obstruction of the hypopharynx by the tongue. Sometimes, they may require a tracheostomy to maintain an adequate airway, [34] and a gastrostomy to assure an adequate caloric intake while protecting the airway. Corrective surgery of the face is performed at defined ages, depending on the developmental state. [35]
An overview of the present guidelines:
Hearing loss in Treacher Collins syndrome is caused by deformed structures in the outer and middle ear. The hearing loss is generally bilateral with a conductive loss of about 50–70 dB. Even in cases with normal auricles and open external auditory canals, the ossicular chain is often malformed. [41]
Attempts to surgically reconstruct the external auditory canal and improve hearing in children with TCS have not yielded positive results. [42]
Auditory rehabilitation with bone-anchored hearing aids (BAHAs) or a conventional bone conduction aid has proven preferable to surgical reconstruction. [38]
The disorder can be associated with a number of psychological symptoms, including anxiety, depression, social phobia, and distress about body image. People who have this disorder may also experience discrimination, bullying, and name calling, especially when young. A multi-disciplinary team and parental support should include these issues. [43]
TCS occurs in about one in 50,000 births in Europe. [44] Worldwide, it is estimated to occur in one in 10,000 to one in 50,000 births. [12]
The syndrome is named after Edward Treacher Collins (1862–1932), the English surgeon and ophthalmologist who described its essential traits in 1900. [7] [8] [45] In 1949, Adolphe Franceschetti and David Klein described the same condition on their own observations as mandibulofacial dysostosis. The term mandibulofacial dysostosis is used to describe the clinical features. [46]
In July 1977, a New York Times article describing new plastic surgery techniques which could partially correct the appearance of those with Treacher Collins syndrome was widely circulated resulting in raised awareness of the disease. [47]
Prior to beginning his comedy career, Bob Saget made a documentary short called "Through Adam's Eyes" documenting his young nephew's experiences undergoing facial reconstructive surgery due to Treacher Collins; the film won a student Academy Award. [48]
The disorder was featured on the show Nip/Tuck , in the episode "Blu Mondae". [49] TLC's Born Without a Face [50] features Juliana Wetmore, who was born with the most severe case in medical history of this syndrome and is missing 30%–40% of the bones in her face. [50]
In 2010, BBC Three documentary Love Me, Love My Face [51] covered the case of a man, Jono Lancaster, with the condition. In 2011, BBC Three returned to Jono to cover his and his partner Laura's quest to start a family, [2] in So What If My Baby Is Born Like Me?, [52] which first aired as part of a BBC Three season of programmes on parenting. [53] The first film was replayed on BBC One shortly ahead of the second film's initial BBC Three broadcast. Lancaster's third BBC Three film, Finding My Family on Facebook, which looked at adoption, aired in 2011. [54] Lancaster's memoir about living with the condition, Not All Heroes Wear Capes, [55] published in 2023.
In Wonder , a children's novel written by R. J. Palacio, the main character is a child who has Treacher Collins syndrome. [56] A 2017 film adaptation of Wonder, starring Julia Roberts, Owen Wilson and Jacob Tremblay, was released in November 2017. [57] [58]
Alison Midstokke, who appears in the drama film Happy Face (2018), [59] is an actress and activist who has the condition.
Anotia describes a rare congenital deformity that involves the complete absence of the auricle, the outer projected portion of the ear, and narrowing or absence of the ear canal. This contrasts with microtia, in which a small part of the auricle is present. Anotia and microtia may occur unilaterally or bilaterally. This deformity results in conductive hearing loss, deafness.
A cleft lip contains an opening in the upper lip that may extend into the nose. The opening may be on one side, both sides, or in the middle. A cleft palate occurs when the palate contains an opening into the nose. The term orofacial cleft refers to either condition or to both occurring together. These disorders can result in feeding problems, speech problems, hearing problems, and frequent ear infections. Less than half the time the condition is associated with other disorders.
Crouzon syndrome is an autosomal dominant genetic disorder known as a branchial arch syndrome. Specifically, this syndrome affects the first branchial arch, which is the precursor of the maxilla and mandible. Because the branchial arches are important developmental features in a growing embryo, disturbances in their development create lasting and widespread effects. The syndrome is caused by a mutation in a gene on chromosome 10 that controls the body's production of fibroblast growth factor receptor 2 (FGFR2).
A coloboma is a hole in one of the structures of the eye, such as the iris, retina, choroid, or optic disc. The hole is present from birth and can be caused when a gap called the choroid fissure, which is present during early stages of prenatal development, fails to close up completely before a child is born. Ocular coloboma is relatively uncommon, affecting less than one in every 10,000 births.
Stickler syndrome is a group of rare genetic disorders affecting connective tissue, specifically collagen. Stickler syndrome is a subtype of collagenopathy, types II and XI. Stickler syndrome is characterized by distinctive facial abnormalities, ocular problems, hearing loss, and joint and skeletal problems. It was first studied and characterized by Gunnar B. Stickler in 1965.
Hemifacial microsomia (HFM) is a congenital disorder that affects the development of the lower half of the face, most commonly the ears, the mouth and the mandible. It usually occurs on one side of the face, but both sides are sometimes affected. If severe, it may result in difficulties in breathing due to obstruction of the trachea—sometimes even requiring a tracheotomy. With an incidence in the range of 1:3500 to 1:4500, it is the second most common birth defect of the face, after cleft lip and cleft palate. HFM shares many similarities with Treacher Collins syndrome.
Microtia is a congenital deformity where the auricle is underdeveloped. A completely undeveloped auricle is referred to as anotia. Because microtia and anotia have the same origin, it can be referred to as microtia-anotia. Microtia can be unilateral or bilateral. Microtia occurs in 1 out of about 8,000–10,000 births. In unilateral microtia, the right ear is most commonly affected. It may occur as a complication of taking Accutane (isotretinoin) during pregnancy.
Treacle protein is a protein that studies suggest is involved in the production of a molecule called ribosomal RNA (rRNA) within cells. Treacle is active in the nucleolus, which is a small region inside the nucleus where rRNA is produced. As a major component of cell structures called ribosomes, rRNA is essential for the assembly of proteins. This protein is active during early embryonic development in structures that become bones and other tissues in the face. Although the precise function of this protein is unknown, researchers believe that it plays a critical role in the development of facial bones and related structures.
Pierre Robin sequence is a congenital defect observed in humans which is characterized by facial abnormalities. The three main features are micrognathia, which causes glossoptosis, which in turn causes breathing problems due to obstruction of the upper airway. A wide, U-shaped cleft palate is commonly also present. PRS is not merely a syndrome, but rather it is a sequence—a series of specific developmental malformations which can be attributed to a single cause.
Hearing loss with craniofacial syndromes is a common occurrence. Many of these multianomaly disorders involve structural malformations of the outer or middle ear, making a significant hearing loss highly likely.
Craniofrontonasal dysplasia is a very rare X-linked malformation syndrome caused by mutations in the ephrin-B1 gene (EFNB1). Phenotypic expression varies greatly amongst affected individuals, where females are more commonly and generally more severely affected than males. Common physical malformations are: craniosynostosis of the coronal suture(s), orbital hypertelorism, bifid nasal tip, dry frizzy curled hair, longitudinal ridging and/or splitting of the nails, and facial asymmetry.
Ablepharon macrostomia syndrome (AMS) is an extremely rare, autosomal dominant genetic disorder characterized by abnormal phenotypic appearances that primarily affect the head and face as well as the skull, skin, fingers and genitals. AMS generally results in abnormal ectoderm-derived structures. The most prominent abnormality is the underdevelopment (microblepharon) or absence of eyelids – signifying the ablepharon aspect of the disease – and a wide, fish-like mouth – macrostomia. Recent scholars and surgeons have called into question the naming of the condition as "Ablepharon" on account of recent investigation and histology showing consistent evidence of at least some eyelid tissue. Infants presenting with AMS may also have malformations of the abdominal wall and nipples. Children with AMS might also experience issues with learning development, language difficulties and intellectual disabilities.
Frontonasal dysplasia (FND) is a congenital malformation of the midface. For the diagnosis of FND, a patient should present at least two of the following characteristics: hypertelorism, a wide nasal root, vertical midline cleft of the nose and/or upper lip, cleft of the wings of the nose, malformed nasal tip, encephalocele or V-shaped hair pattern on the forehead. The cause of FND remains unknown. FND seems to be sporadic (random) and multiple environmental factors are suggested as possible causes for the syndrome. However, in some families multiple cases of FND were reported, which suggests a genetic cause of FND.
Macrostomia refers to a mouth that is unusually wide. The term is from the Greek prefix makro- meaning "large" and from Greek στόμα, "mouth".
Miller syndrome, also known as Genée–Wiedemann syndrome, Wildervanck–Smith syndrome or postaxial acrofacial dysostosis, is an extremely rare genetic condition that manifests as craniofacial, limb and eye deformities. It is caused by a mutation in the DHODH gene. The incidence of the condition is not known, and little is known about its pathogenesis.
Roberts syndrome, or sometimes called pseudothalidomide syndrome, is an extremely rare autosomal recessive genetic disorder that is characterized by mild to severe prenatal retardation or disruption of cell division, leading to malformation of the bones in the skull, face, arms, and legs.
A facial cleft is an opening or gap in the face, or a malformation of a part of the face. Facial clefts is a collective term for all sorts of clefts. All structures like bone, soft tissue, skin etc. can be affected. Facial clefts are extremely rare congenital anomalies. There are many variations of a type of clefting and classifications are needed to describe and classify all types of clefting. Facial clefts hardly ever occur isolated; most of the time there is an overlap of adjacent facial clefts.
Malpuech facial clefting syndrome, also called Malpuech syndrome or Gypsy type facial clefting syndrome, is a rare congenital syndrome. It is characterized by facial clefting, a caudal appendage, growth deficiency, intellectual and developmental disability, and abnormalities of the renal system (kidneys) and the male genitalia. Abnormalities of the heart, and other skeletal malformations may also be present. The syndrome was initially described by Georges Malpuech and associates in 1983. It is thought to be genetically related to Juberg-Hayward syndrome. Malpuech syndrome has also been considered as part of a spectrum of congenital genetic disorders associated with similar facial, urogenital and skeletal anomalies. Termed "3MC syndrome", this proposed spectrum includes Malpuech, Michels and Mingarelli-Carnevale (OSA) syndromes. Mutations in the COLLEC11 and MASP1 genes are believed to be a cause of these syndromes. The incidence of Malpuech syndrome is unknown. The pattern of inheritance is autosomal recessive, which means a defective (mutated) gene associated with the syndrome is located on an autosome, and the syndrome occurs when two copies of this defective gene are inherited.
Branchio-oculo-facial syndrome (BOFS) is a disease that arises from a mutation in the TFAP2A gene. It is a rare autosomal dominant disorder that starts to affect a child's development before birth. Symptoms of this condition include skin abnormalities on the neck, deformities of the ears and eyes, and other distinctive facial features such a cleft lip along with slow growth, mental retardation and premature graying of hair.
Craniofacial regeneration refers to the biological process by which the skull and face regrow to heal an injury. This page covers birth defects and injuries related to the craniofacial region, the mechanisms behind the regeneration, the medical application of these processes, and the scientific research conducted on this specific regeneration. This regeneration is not to be confused with tooth regeneration. Craniofacial regrowth is broadly related to the mechanisms of general bone healing.