## **Core Concept**
X-linked dominant conditions are genetic disorders caused by mutations in genes on the X chromosome. These conditions exhibit a dominant pattern of inheritance, meaning a single copy of the mutated gene is enough to cause the disorder. Females, having two X chromosomes, are more frequently affected but often less severely than males, who have one X and one Y chromosome.

## **Why the Correct Answer is Right**
The correct answer, , is an example of an X-linked dominant condition. This condition results from mutations in a specific gene located on the X chromosome. The disorder leads to characteristic clinical features that can vary in severity between affected males and females. The X-linked dominant pattern of inheritance explains the observed gender distribution and severity of symptoms.

## **Why Each Wrong Option is Incorrect**
- **Option A:** is incorrect because it does not represent an X-linked dominant condition. It might be associated with a different inheritance pattern.
- **Option B:** is incorrect as it is not characterized by X-linked dominant inheritance. It could be linked to an autosomal or other type of genetic inheritance.
- **Option C:** is incorrect because, similar to options A and B, it does not follow the X-linked dominant pattern of inheritance.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that X-linked dominant disorders can often present with milder symptoms in females compared to males due to X-chromosome inactivation patterns. A classic example of an X-linked dominant condition is **Vitamin D-resistant rickets**, also known as X-linked hypophosphatemia.

## **Correct Answer:** .