## **Core Concept**
Wilson's disease, also known as hepatolenticular degeneration, is a genetic disorder characterized by excessive accumulation of copper in the body, particularly in the liver, brain, and other vital organs. This condition is inherited in an autosomal recessive pattern. The disease is caused by mutations in a specific gene that plays a crucial role in regulating copper transport.

## **Why the Correct Answer is Right**
The correct answer, **ATP7B**, is the gene responsible for Wilson's disease. The **ATP7B** gene provides instructions for making a protein called copper-transporting ATPase 2, which plays a critical role in regulating the transport of copper from the liver to other parts of the body and in removing excess copper from the body. Mutations in the **ATP7B** gene lead to impaired copper transport and excretion, resulting in copper accumulation and toxicity.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While **ATP7A** is indeed a copper-transporting ATPase, mutations in **ATP7A** are associated with Menkes disease, a different disorder characterized by copper deficiency, not Wilson's disease.
- **Option C and D:** These options are not directly related to the primary cause of Wilson's disease.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl for Wilson's disease is that it can present with a combination of liver disease, neurological symptoms, and psychiatric problems. A classic diagnostic feature is the Kayser-Fleischer ring, which is a copper deposit in the cornea of the eye. Early diagnosis and treatment, often with penicillamine or zinc acetate, can significantly improve outcomes.

## **Correct Answer:** . **ATP7B**