## **Core Concept**
Enzyme replacement therapy (ERT) is a medical treatment in which an deficient or absent enzyme is replaced with a healthy copy of that enzyme. This approach is used to treat various genetic disorders caused by enzyme deficiencies. ERT has been developed for several diseases, including lysosomal storage disorders.

## **Why the Correct Answer is Right**
ERT is available for **Gaucher's disease**, which is a genetic disorder caused by a deficiency of the enzyme **glucocerebrosidase**. This deficiency leads to the accumulation of glucocerebroside within cells, particularly in the liver, spleen, and bone marrow. The recombinant form of glucocerebrosidase is used as an ERT to help break down the accumulated glucocerebroside, thereby alleviating symptoms.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, although it's a genetic disorder, ERT details are not provided; however, we can confirm that not all genetic disorders have ERT available.
- **Option B:** This option is incorrect because it does not directly correspond with known ERT treatments widely recognized like Gaucher's.
- **Option C:** This option is incorrect as there's no widely known ERT for this condition listed here; specifics would depend on the actual disease.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that Gaucher's disease is one of the lysosomal storage diseases for which ERT is specifically available. This treatment has significantly improved the management and quality of life for patients with Gaucher's disease. Another notable example of a disease treated with ERT is **Fabry disease**, where the enzyme **alpha-Gal A** is replaced.

## **Correct Answer:** B. Gaucher's disease.