Which of the following is an X-Linked disorder?
**Core Concept**
X-linked disorders are genetic conditions caused by mutations in genes located on the X chromosome. These disorders are more common in males, who have only one X chromosome, as a single copy of the mutated gene can cause the condition. Females, who have two X chromosomes, are typically carriers of the mutated gene and may exhibit milder symptoms or be asymptomatic.
**Why the Correct Answer is Right**
The correct answer is a condition that is caused by a mutation in a gene located on the X chromosome. In this case, the condition is caused by a deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD), which is essential for protecting red blood cells from oxidative damage. The G6PD gene is located on the X chromosome, and mutations in this gene can lead to X-linked G6PD deficiency. This condition is more common in males, who are more likely to be affected by the mutation, and may exhibit symptoms such as hemolytic anemia after exposure to certain medications or foods.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is not an X-linked disorder. It is a condition caused by a deficiency of the enzyme phenylalanine hydroxylase, which is located on an autosome (chromosome 12). Females can be affected by this condition, and it is not more common in males.
* **Option B:** This option is incorrect because it is a condition caused by a mutation in the CFTR gene, which is located on chromosome 7. It is not an X-linked disorder and is not more common in males.
* **Option C:** This option is incorrect because it is a condition caused by a mutation in the HFE gene, which is located on chromosome 6. It is not an X-linked disorder and is not more common in males.
**Clinical Pearl / High-Yield Fact**
X-linked disorders are more common in males due to the presence of only one X chromosome. Females can be carriers of these conditions and may exhibit milder symptoms or be asymptomatic. It is essential to consider the possibility of X-linked inheritance in patients with certain conditions, particularly those that are more common in males.
**Correct Answer: D. G6PD deficiency**