Treacher collins syndrome Flashcards
what causes Treacher collins syndrome ?
when NCC do not migrate to the pharyngeal arches to form cranifacial structures
what pharyngeal arches are affected by TCS?
1st and 2nd
Is TCS genetically and phenotypically heterogenous or homogenous?
heterogenous
what gene is the majority of TCS mutations in?
TCOF1
what genes are the minority of TCS mutations in?
POLR1D and POLR1C
what protein does TCOF1 encode?
treacle protein
what proteins do POLR1D and POLR1C encode?
rna pol 1 and 111
what is rna polymerase important in?
rna synthesis
what does TCS cause?
aplasia of facial bones- underdeveloped facial bones
name some features of TCS
-middle ear deformaties
-orbital deformaties
-zygomatic and mandibular deformaties
-clefts
-small jaw and chin
what can also be seen in 50% of TCS patients?
hearing loss
what is a life threatening problem that can occur in TCS newborns?
respiratory problems due to airway narrowing
what is the treatment of TCS?
-early intervention of respiratory, hearing speech. etc
-facial reconstruction
-hearing aids or middle ear surgery
what type of inheritance is the TCOF1 mutation?
autosomal dominance
what does autosomal dominance mean?
non-sex chromosome
- only need single copy of mutated gene from parent
what type of inheritance is POLR1D and POLR1C?
autosomal dominant and autosomal recessive
what does autosomal recessive mean?
non sex chromosome
-requires a copy of mutated gene from both parents
what does it mean when some mutations occur spontaneously?
they are not inherited from the parents
what are the majority of mutations seen in TCOF1?
deletion mutations
what does the deletion mutation in TCOF1 result in?
turnacated treacle protein- meaning it is small and non functioning
where is treacle found to be active?
in embryonic developmental tissues than become bone and other tissues of the face
what does the treacle protein do?
ribosomal processing and making of ribosomes
what happens when TCOF1 is depleted in mice?
causes depletion of NCC cells through cell death- reduced no of NCC cells that migrate to CF complex
