A. 1st arch defect.
B. 2nd arch defect.
C. 3rd arch defect.
D. 4th arch defect.
Ans:A. First Arch Defect
The image shown is of Treacher Collins syndrome.
- First arch syndromes are congenital defects caused by a failure of neural crest cells to migrate into the first pharyngeal arch.
They can produce facial anomalies.
Examples of first arch syndromes include Treacher Collins syndrome and Pierre Robin syndrome.
- Treacher Collins syndromeis an autosomal dominant congenital disorder characterized by craniofacial deformities, involving the ears, eyes, cheekbones, and jawbone. Those affected have normal intelligence.
The typical physical features include downward-slanting eyes, micrognathia (a small lower jaw), conductive hearing loss, underdeveloped zygomatic bones, drooping part of the lateral lower eyelids, and malformed or absent ears.
- Pierre Robin Syndrome is characterized by an unusually small mandible (micrognathia), posterior displacement or retraction of the tongue (glossoptosis), and upper airway obstruction.