Treacher Collins Syndrome (TCS)

Question 1

what is treacher collins syndrome?

Answer 1

a congenital (present at birth) condition affecting the bones and tissue in the face

Question 2

TCS is caused by abnormal formation of which branchial (pharyngeal arches) during what weeks of human fetal development?

Answer 2

caused by an abnormal formation of the 1st and 2nd branchial arches during the 5th to 8th week of human foetal development, leading to profound facial dysmorphism

Question 3

what is the most common mutation in TCS

Answer 3

loss of function mutations in the gene TCOF1 which encodes the protein treacle

Question 4

Apart from TCOF1, what are other mutations which can cause TCS?

Answer 4

mutations to the genes POLR1D and POLR1C, which encode the subunits of the enzymes RNA polymerase I and III, important for RNA synthesis

Question 5

Some people with TCS are also born with what?

Answer 5

a cleft palate

Question 6

What are the most common underdeveloped facial bones in TCS

Answer 6

cheek bones, eye sockets and a very small jaw and chin (micrognathia)

Question 7

What are the facial features of a patient with TCS?

Answer 7

eyes that slant downwards, sparse eyelashes, eyelid coloboma

some eye abnormalities may cause loss of vision

also characterised by absent, small or unusually formed ears - hearing loss occurs in about 1/2 of affected individuals

Question 8

What is the main concern in newborn TCS patients?

Answer 8

Respiratory failure due to airway narrowing from craniofacial malformation

Question 9

What is treatment like for TCS patients?

Answer 9

Early intervention is needed to clear and maintain the airway, enable feeding, protect the eyes, improve hearing and speech development
Later on, aesthetic and functional reconstructions of the mouth, face and external ear may occur
Bone conduction hearing aids or middle ear surgery are usually used to improve hearing in these patients

Question 10

what kind of inherent pattern is the TCOF1 mutation

Answer 10

inherited via and autosomal dominant pattern (not on a sex chromosome)

Question 10

True or False: Some TCS gene mutations occur spontaneously (not inherited from their parents)

Answer 10

True

Question 10

What kind of inherent pattern is the POLR1D and POLR1C mutations

Answer 10

POLR1D = autosomal dominant
POLR1C = autosomal recessive

Question 10

What is the function of the treacle protein?

Answer 10

Plays a key role in pre-ribosomal processing and making of the ribosome