## **Core Concept**
Mucopolysaccharidosis (MPS) is a group of inherited disorders caused by the deficiency of enzymes needed to break down and recycle sugar molecules within cells. This leads to the accumulation of glycosaminoglycans (GAGs) in various tissues, resulting in cellular dysfunction. The diseases are characterized by distinct clinical features, including corneal clouding, which is common in many types.

## **Why the Correct Answer is Right**
The correct answer, , is associated with a specific type of mucopolysaccharidosis that presents with clear corneas. Mucopolysaccharidosis type II (Hunter syndrome), caused by a deficiency of iduronate-2-sulfatase, is known for its clinical presentation that includes severe progressive neurological symptoms and physical findings. Unlike many other types of MPS, patients with Hunter syndrome typically do not have corneal clouding, making their corneas appear clear.

## **Why Each Wrong Option is Incorrect**
* **Option A:** - This type of MPS often presents with corneal clouding due to the accumulation of dermatan sulfate and heparan sulfate, making clear corneas an unlikely feature.
* **Option B:** - This MPS type is characterized by the accumulation of keratan sulfate and chondroitin-6-sulfate, and corneal clouding is a common finding, contrary to clear corneas.
* **Option C:** - In this condition, corneal clouding is present due to the accumulation of GAGs, similar to other MPS types with corneal involvement.

## **Clinical Pearl / High-Yield Fact**
A key clinical feature to remember is that Hunter syndrome (MPS II) is one of the few mucopolysaccharidoses that does not present with corneal clouding, making it stand out among the MPS types. This is crucial for differentiating it from other MPS disorders.

## **Correct Answer:** . Hunter syndrome