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Treacher Collins syndrome

Treacher Collins syndrome (TCS) is a genetic craniofacial condition involving the formation of the face and skull bones. It mostly affects the eyes, cheekbones, ears, jaw and chin, and especially the airway. The severity of the syndrome varies widely among affected individuals. Since the syndrome causes deficient bone in the skull and face, characteristics and symptoms include:

  • High forehead
  • Downward-slanting eyes and often notching at the corners (coloboma)
  • Eyesight issues
  • Missing or sparse lower eyelashes
  • Underdeveloped cheekbones (malar hypoplasia) 
  • Small low-set, cupped or absent/malformed shaped outer ears (microtia)
  • Middle ear bone malformations
  • Narrowing or blocked nasal cavity (choanal stenosis or atresia)
  • Opening in roof of mouth (cleft palate) or submucous cleft palate
  • Very small/recessed jaw (micrognathia)
  • Airway complications (sometimes a need for tracheostomy for breathing)
  • Eating and speech difficulties
  • Conductive hearing loss often requiring hearing aids or hearing processors
  • Less common is an opening in upper lip (cleft lip)
  • Individuals born with TCS typically have normal to above-average intelligence.

how rare is Treacher Collins syndrome?

One in every 20,000 births results in Treacher Collins syndrome. Sixty percent of the time, a mutation/variant occurs and causes the syndrome. The other forty percent of the time, it is passed down from one of the parents.

are kids born with Treacher Collins syndrome?

Yes. Treacher Collins syndrome occurs at some point in the pregnancy and is caused by a genetic mutation change (now more commonly called a genetic variant) from one of four different genes on four different chromosomes. Therefore, a baby born with TCS either inherited it from the parent(s), or it was a spontaneous occurrence. An individual affected with TCS has a fifty percent chance of passing it on to any offspring. 

what is the life expectancy of someone with Treacher Collins syndrome?

Even though surgeries are often in their future, they can have a typical life span just like anyone else.

how do I know if my child will be born with TCS?

If you have TCS and know your genetic variant location, your fetus can be tested for the same family variant to determine if positive for the syndrome. If you do not know your variant location, then other testing (ultrasounds, etc.) can be done to look for risk factors such as cleft issues or malformed external ears. While any testing may tell you if your baby will have TCS or not, it cannot tell you the specific features or severity. Extra amniotic fluid (polyhydramnios) is sometimes present during a positive pregnancy for TCS due to the fetus not being able to swallow sufficiently; this is often a reason for more in-depth testing.  

After birth, an exam may be all that is needed to determine if a child has TCS. Further exams will help clarify severity, while genetic testing can identify family members who may also be affected.

what are the genes responsible for Treacher Collins syndrome?

To date, there are four genes responsible for Treacher Collins syndrome:

  • Treacher Collins syndrome-1 (TCS1); gene Tcof1; chromosome 5/gene location 5q32-q33; inheritance 86%; autosomal dominant
  • Treacher Collins syndrome-2 (TCS2); gene Polr1d; chromosome 13/gene location- 13q12.2; inheritance 6%; autosomal dominant or recessive
  • Treacher Collins syndrome-3 (TCS3); gene Polr1c; chromosome 6/gene location 6p21.1; inheritance 1.2%; autosomal recessive
  • Treacher Collins syndrome-4 (TCS4); gene Polr1b; chromosome 2/gene location 2q14.1; inheritance 1.3%; autosomal dominant

how do you treat TCS?

Treatment is focused on function and correcting facial structures. This can involve craniofacial surgery for enlarging the airway and procedures such as cleft palate repair. A child with TCS may see different specialties and doctors during their lifetime which include reconstructive craniofacial surgery, ophthalmology, pulmonology, otolaryngology (ENT), orthodontics and dental care.