## **Core Concept**
X-linked recessive disorders are a group of genetic conditions that are caused by mutations in genes on the X chromosome. These disorders are more common in males because they have only one X chromosome. If that X chromosome has a mutation, they will express the condition since they do not have another X chromosome to compensate.

## **Why the Correct Answer is Right**
The correct answer, , is an example of an X-linked recessive disorder. This condition results from a deficiency of factor VIII, a crucial protein for blood clotting, due to mutations in the F8 gene located on the X chromosome. Males are more frequently affected than females because males have one X and one Y chromosome (XY). If the X chromosome carries the mutation, males will express the condition. Females, on the other hand, would need both X chromosomes to carry the mutation to express the condition, making it less common in females.

## **Why Each Wrong Option is Incorrect**
- **Option A:** is not an X-linked recessive disorder; it is an autosomal dominant disorder. It affects the gene for the low-density lipoprotein receptor, leading to high cholesterol levels. This condition does not follow the X-linked pattern of inheritance.
- **Option B:** is an autosomal recessive disorder. It results from mutations in the HBB gene that codes for the beta-globin subunit of hemoglobin, leading to abnormal hemoglobin. This condition does not exhibit X-linked recessive inheritance.
- **Option C:** could potentially refer to several conditions, but if it's considered in the context of common genetic disorders, there's no well-known X-linked condition directly referenced here that matches the profile of being a classic X-linked recessive disorder like .

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl for X-linked recessive disorders, such as , is that affected males will pass the mutated gene to all their daughters (making them obligate carriers) but not to their sons. Carrier females have a 50% chance of passing the mutated gene to each child. Sons who inherit the mutated gene will be affected, while daughters who inherit it will typically be carriers.

## **Correct Answer:** .