**Question:** Which of the following is a feature of Marfan's syndrome?

A. Long, thin limbs and fingers with loose joints
B. Protruding eyes with corneal opacities
C. Short stature and obesity
D. Dental abnormalities, such as malformed teeth and delayed tooth eruption

**Core Concept:** Marfan's syndrome is a genetic disorder affecting the connective tissue, primarily involving the cardiovascular, skeletal, and ocular systems. It is caused by mutations in the FBN1 gene, which encodes for fibrillin-1 protein, a component of microfibrils that provide structural support to tissues.

**Why the Correct Answer is Right:** A is correct because Marfan's syndrome is characterized by long, slender limbs, hypermobility, and protruding eyes due to abnormal development of the skeletal, cardiovascular, and ocular systems. Fibrillin-1 protein is essential for maintaining tissue integrity and elasticity, and mutations lead to defective microfibril production and impaired tissue repair, resulting in the described clinical features.

**Why Each Wrong Option is Incorrect:**

B (protruding eyes with corneal opacities) is incorrect because corneal opacities are not a common feature of Marfan's syndrome, but are more commonly associated with keratoconus. Protruding eyes are generally caused by the elongation of the eyeball and optic nerve head, which can lead to glaucoma and vision impairment.

C (short stature and obesity) is incorrect because Marfan's syndrome is typically associated with tall stature, although height can be reduced in severe cases. Obesity is rare and not a defining feature of the condition.

D (dental abnormalities, such as malformed teeth and delayed tooth eruption) is incorrect because dental abnormalities are less common than the other clinical features and may occur concurrently with other dental issues unrelated to Marfan's syndrome. Delayed tooth eruption is rare and not specific to Marfan's syndrome.

**Clinical Pearl:** Marfan's syndrome is a complex disorder involving multiple organ systems. It is essential for medical students to understand the key features, such as long limbs, joint hypermobility, and cardiovascular anomalies, to correctly diagnose and manage patients with suspected Marfan's syndrome.