Question
The defect as shown in the picture below occurs due to defect in which of the following arches?
A. 1st arch defect.
B. 2nd arch defect.
C. 3rd arch defect.
D. 4th arch defect.
Show Answer
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Correct Answer » A
Explanation
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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.
