image.png
for this image give 3 mark question for spotting
analyse_media
Reading File
The image shows two individuals with features classic for Treacher Collins Syndrome (Mandibulofacial Dysostosis). Here is a well-structured 3-mark spotting question:
SPOTTING QUESTION (3 Marks)
"A photograph shows two young individuals in profile view. Both exhibit severe micrognathia/retrognathia, malar hypoplasia, downslanting palpebral fissures, lower eyelid coloboma, and bilateral microtia."
Q. What is the diagnosis? Describe the visible clinical features seen in this image. What is the genetic basis of this condition?
ANSWER (3 Marks)
1. Diagnosis (1 mark)
Treacher Collins Syndrome (also called Mandibulofacial Dysostosis)
- It results from abnormal development of structures derived from the 1st and 2nd pharyngeal arches.
2. Clinical Features visible in the image (1 mark) - any 4:
- Micrognathia / Retrognathia - severely underdeveloped, receding lower jaw and chin
- Malar hypoplasia - underdevelopment of the zygomatic (cheek) bones, giving a flat midface
- Downslanting palpebral fissures (anti-Mongoloid slant)
- Lower eyelid coloboma - notching/defect of the lower eyelids
- Bilateral microtia - small, malformed, low-set external ears (associated with conductive hearing loss due to external auditory canal atresia)
- Prominent/beaked nose - a relative prominence due to surrounding hypoplasia
3. Genetic Basis (1 mark)
- Autosomal dominant inheritance (though 40% are de novo mutations)
- Most commonly caused by mutation in the TCOF1 gene (encodes the protein Treacle, involved in ribosome biogenesis)
- Less commonly: mutations in POLR1C or POLR1D genes (autosomal recessive forms)
- Pathophysiology: disrupted neural crest cell development during weeks 3-4 of embryogenesis
Differential diagnoses to mention: Nager syndrome, Miller syndrome, Pierre Robin sequence (but these lack the bilateral symmetry and full constellation of TCS features).
This is a shared conversation. Sign in to Orris to start your own chat.