Which of the following is not observed in cri-du-chat syndrome?
**Core Concept**
Cri-du-chat syndrome is a genetic disorder caused by a partial deletion of the short arm of chromosome 5. It is characterized by a range of physical and developmental abnormalities. This condition is associated with a high-pitched cry, intellectual disability, and various physical anomalies.
**Why the Correct Answer is Right**
Cri-du-chat syndrome is typically associated with a high-pitched cry, intellectual disability, microcephaly, and a range of physical anomalies such as a small head, wide-set eyes, and a small jaw. The correct answer should reflect a feature not commonly observed in this condition.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a high-pitched cry is a hallmark of cri-du-chat syndrome.
**Option B:** This option is incorrect because intellectual disability is a common feature of cri-du-chat syndrome.
**Option C:** This option is incorrect because microcephaly is a common feature of cri-du-chat syndrome.
**Option D:** This option is incorrect because a small jaw is a common feature of cri-du-chat syndrome.
**Clinical Pearl / High-Yield Fact**
Cri-du-chat syndrome is often associated with a high-pitched cry that sounds like a cat's meow, which is how it got its name. This distinctive cry is usually present in the first few weeks of life and may fade as the child gets older.
**Correct Answer: D. A normal-sized jaw.**