Cardiac anomaly seen in Noonan’s syndrome is
**Core Concept**
Noonan's syndrome is a genetic disorder characterized by unique facial features, short stature, heart defects, and other physical abnormalities. Cardiac anomalies are a common feature of Noonan's syndrome, and understanding the underlying cardiac defect is crucial for diagnosis and management.
**Why the Correct Answer is Right**
The cardiac anomaly most commonly associated with Noonan's syndrome is a right-sided obstructive lesion, specifically pulmonary stenosis. This is due to mutations in the PTPN11 gene, which encodes a protein involved in the RAS/MAPK signaling pathway. Abnormal activation of this pathway leads to hypertrophic cardiomyopathy and valve abnormalities, including pulmonary stenosis. The increased resistance to blood flow through the pulmonary valve results in right ventricular hypertrophy and potential heart failure.
**Why Each Wrong Option is Incorrect**
* **Option A:** While septal defects are common in various congenital heart diseases, they are not the primary cardiac anomaly associated with Noonan's syndrome.
* **Option B:** Hypertrophic cardiomyopathy is a feature of Noonan's syndrome, but it is not the most specific or characteristic cardiac anomaly.
* **Option D:** Atrial septal defects are more commonly associated with other genetic syndromes, such as Down syndrome.
**Clinical Pearl / High-Yield Fact**
Noonan's syndrome is often associated with other systemic features, including short stature, webbed neck, low-set ears, and skeletal abnormalities. Recognizing these characteristic physical features is essential for early diagnosis and management.
**Correct Answer: C. Pulmonary stenosis.**