Treacher-Collins syndrome

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Treacher-Collins syndrome
Classification and external resources
DiseasesDB 13267


Treacher Collins Syndrome (mandibulofacial dysostosis)

Disease Entity

Treacher Collins syndrome (TCS), or mandibulofacial dysostosis, is a genetic condition characterized by abnormalities in first branchial arch structures which may affect the eyes, ears, and various facial bones. The treatment of TCS is multidisciplinary and changes with the development of the child.

Etiology

Treacher Collins syndrome has been associated with mutations in TCOF1, POLR1C, and POLR1D. TCOF1 is the most common mutation accounting for 81 to 93 percent of all diagnosed cases of TCS.[1] POLR1C and POLR1D mutations account for approximately two percent of additional diagnosed cases. The genetic cause of TCS in individuals without one of the aforementioned genetic mutations is currently unknown.

The inheritance pattern for TCS resulting from mutations in TCOF1 or POLR1D is autosomal dominant.[1] Approximately 60 percent of these cases arise from de novo mutations, while the remaining cases occur secondary to inheritance of the altered gene from an affected parent.[1] TCS occurring secondary to mutations in the POLR1C gene follows an autosomal recessive pattern of inheritance.

Treacher Collins syndrome is estimated to affect 1:50,000 people.

Diagnosis

The clinical findings are highly variable but general findings may include: Tessier clefts 6-8, hypoplasia of malar and zygomatic bones with decreased inferolateral orbital angles, hypoplastic lower jaw with abnormal dentition, choanal atresia and mandibular retrusion, external ear malformations and conductive hearing loss.[2][3]

Ocular findings in Treacher Collins syndrome include: colobomas of the lateral aspect of the lower lid, antimongoloid slant of the palpebral fissures, canthal dystopia, atresia of lower lacrimal puncta and canaliculus, ectropion, orbital and limbal dermoids, and high astigmatism in severe cases.[2][3]

History

Family history, Difficulty with feeding or hearing.

  • Diagnostic procedures
  • Cephalometry, audiology, and dental evaluation

Laboratory test

Genetic Testing

Differential diagnosis

  • Goldenhar syndrome: Goldenhar syndrome was originally characterized by epibulbar dermoids, preauricular appendages, and mandibular hypoplasia. It was later expanded to oculoauriculovertebral dysostosis and includes cardiac, renal, vertebral, pulmonary, and central nervous system abnormalities. Other ocular findings that may be seen in Goldenhar syndrome include dermolipoma, coloboma of the iris and upper lid, microphthalmos, disturbances in ocular motility, ptosis, and nasolacrimal duct abnormailities.[3]
  • Nager syndrome: Nager syndrome is a type of acrofacial dysostosis that is associated with malar hypoplasia, micrognathia, cleft palate, conductive hearing loss, malformed or absent thumbs, clinodactyly, and syndactyly. Ocular findings in Nager syndrome may include downward slanting eyes, absent eyelashes, and lower eyelid coloboma.[4]
  • Maxillofacial dysostosis: Findings in Maxillofacial dysostosis include a hypoplastic maxilla, downward slanting palpebral fissures, external ear malformations, and speech abnormalities.[5] Ocular abnormalities that may be seen in this disorder include ptosis, strabismus, and nystagmus.[5]

Management

The management of TCS is multidisciplinary and is generally classified into three categories based on the age of the individual.

Birth to 2 years

  • Newborn: Airway and feeding problems should be addressed at this time. Airway management, mandibular distraction, tracheostomy placement, social work, and speech pathology consult to monitor feeding process are all treatment considerations occurring at this time.
  • First three months: Ophthalmology examination to evaluate vision and perform examination of cornea. Continued monitoring of feeding progress occurs during this time. As conductive hearing loss may occur regardless of the appearance of the external ear, patients should undergo audiology evaluation with appropriate referral to ENT as needed. Dental evaluation, genetic counseling, and initial photographs of the patient should also occur during this time period.
  • Three months to two years: Continued ENT and audiology follow up and annual ophthalmology examination, photography, and speech pathology visits. Patient may require palate surgery at this time and should have orthodontic consultation to determine future dental management.

2 years to 12 years

Continued regular follow up as indicated with respiratory, ENT, audiology, dental, speech pathology, orthodontics, ophthalmology, social work, and photography. Patients may undergo repair of zygomatic/orbital clefts and eyelids between the ages of 2-5 years old and have annual follow up with craniofacial surgeon for touch up surgery as required. Patients should obtain cephalometry at ages 4.5 years old and annually starting at age 6 to plot facial growth.

13 years to 18 year

Annual follow ups with ophthalmology, dental, orthodontics, ENT, social work, radiology, photography, and craniofacial surgery. Respiratory, audiology, and speech pathology may be seen as needed during this time. Patients may receive orthognathic surgery during this time and possible revision or repeat bone grafting to zygomatic clefts. [6]

Surgery

Patients may require tracheostomy, palate surgery, orthognathic surgery, and possible revision or repeat bone grafting to zygomatic clefts.

Eyelid surgeries can be complex and require multiple or step-wise procedures, and include eyelid coloboma repair, ptosis repair, and ectropion or lower eyelid retraction surgery to reposition the eyelid to the ocular surface.

References

  1. 1.0 1.1 1.2 U.S. National Library of Medicine. Treacher Collins syndrome. Genetics Home Reference. https://ghr.nlm.nih.gov/condition/treacher-collins-syndrome. Accessed March 21, 2017.
  2. 2.0 2.1 Forbes BJ, Pierce EA. Chapter 330: Osseous and Musculoskeletal Disorders. In: Albert DM, Miller JW, Azar DT, Blodi BA. Albert & Jakobiec’s Principles & Practice of Ophthalmology. 3rd ed. Philadelphia, PA: Saunders; 2008:4495-4516.
  3. 3.0 3.1 3.2 Black J, Crompton J. Chapter 28: Craniofacial abnormalities. In: Lambert SR, Lyons CJ. Taylor and Hoyt’s Pediatric Ophthalmology and Strabismus. 5th ed. Edinburgh, Scotland: El Sevier; 2017:250-266
  4. U.S. National Library of Medicine. Nager syndrome. Genetics Home Reference. https://ghr.nlm.nih.gov/condition/nager-syndrome. Accessed March 21, 2017.
  5. 5.0 5.1 National Organization for Rare Disorders. Maxillofacial Dysostosis. National Organization for Rare Disorders. https://rarediseases.org/rare-diseases/maxillofacial-dysostosis/. Accessed March 21, 2017.
  6. Thompson JT, Anderson PJ, David DJ. Treacher Collins syndrome: protocol management from birth to maturity. J Craniofac Surg. 2009;20:2028–2035.