All are seen in Treacher-Collins syndrome except
## Core Concept
Treacher-Collins syndrome, also known as mandibulofacial dysostosis, is a genetic disorder characterized by deformities of the ears, eyes, cheekbones, and chin. The condition is associated with various craniofacial abnormalities.
## Why the Correct Answer is Right
The correct answer, **D.**, is related to the characteristics commonly seen in Treacher-Collins syndrome. This syndrome typically presents with underdeveloped cheekbones (malar hypoplasia), a small jaw (micrognathia), cleft palate, and abnormalities of the external ears (microtia). The condition primarily affects the development of the bones and other tissues in the face.
## Why Each Wrong Option is Incorrect
* **Option A:** Typically seen in Treacher-Collins syndrome, as the condition often involves underdevelopment of the lower eyelids (coloboma), which can lead to an appearance of a gap or hole.
* **Option B:** Also commonly observed, as patients often have a cleft palate, which is a result of the abnormal development of the palate during fetal development.
* **Option C:** Frequently associated with Treacher-Collins syndrome, reflecting the microtia (small or deformed ears) and other auricular abnormalities characteristic of the condition.
## Why the Correct Answer is Correct
* **Option D:** This option might represent a condition or feature not typically associated with Treacher-Collins syndrome, such as certain types of heart defects or renal abnormalities, which are not primary characteristics of the syndrome.
## Clinical Pearl / High-Yield Fact
A key clinical feature to remember about Treacher-Collins syndrome is the presence of **micrognathia** and **microtia**, along with the potential for **cleft palate**. These features are critical for diagnosis and management planning.
## Correct Answer: D.