**Core Concept**
Anterior lenticonus is a rare, congenital condition characterized by a conical protrusion of the anterior surface of the lens in the eye. It is a hallmark of a specific genetic disorder that affects the structure and function of the collagen in the body.

**Why the Correct Answer is Right**
Alport's syndrome is a genetic disorder caused by mutations in the COL4A3, COL4A4, or COL4A5 genes, which encode for type IV collagen. Type IV collagen is crucial for the structure and function of the glomerular basement membrane in the kidneys and the lens capsule in the eye. In Alport's syndrome, the abnormal collagen leads to the formation of anterior lenticonus, which can cause vision loss and other systemic complications. The characteristic conical protrusion of the anterior lens capsule is a distinctive feature of Alport's syndrome, making it a key diagnostic criterion.

**Why Each Wrong Option is Incorrect**
**Option A:** Lowe's syndrome, also known as oculocerebrorenal syndrome, is a rare genetic disorder characterized by congenital cataracts, intellectual disability, and kidney disease. While it affects multiple systems, it is not associated with anterior lenticonus.

**Option B:** William's syndrome is a genetic disorder caused by a deletion of genes on chromosome 7. It is characterized by distinctive facial features, intellectual disability, and cardiovascular anomalies. Anterior lenticonus is not a feature of William's syndrome.

**Option D:** Down's syndrome is a genetic disorder caused by an extra copy of chromosome 21. It is characterized by intellectual disability, delayed speech, and distinctive facial features. While individuals with Down's syndrome may have various eye abnormalities, anterior lenticonus is not a characteristic feature.

**Clinical Pearl / High-Yield Fact**
When evaluating a patient with anterior lenticonus, it is essential to consider Alport's syndrome as a potential underlying cause. A comprehensive evaluation, including genetic testing, renal function assessment, and family history, is crucial for making an accurate diagnosis and initiating appropriate management.

**✓ Correct Answer: C. Alport's syndrome**