Which is autosomal dominant
**Core Concept**
Autosomal dominant conditions arise from a single copy of a dominant allele, leading to the expression of the disorder in every generation. This means that a single copy of the mutated gene is enough to cause the condition, and individuals with the mutation have a 50% chance of passing it to their offspring.
**Why the Correct Answer is Right**
The correct answer is an example of a genetic disorder that follows an autosomal dominant pattern of inheritance. This means that the mutated gene responsible for the condition is located on one of the non-sex chromosomes (autosomes) and only one copy of the gene is needed to cause the disorder. The condition is often expressed in every generation, and individuals with the mutation have a 50% chance of passing it to their offspring.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not follow an autosomal dominant pattern of inheritance. Conditions that are recessive or X-linked may exhibit different patterns of inheritance.
**Option B:** This option is incorrect because it is not a recognized autosomal dominant disorder. While some conditions may have a similar presentation, they do not follow the same pattern of inheritance.
**Option C:** This option is incorrect because it is not a valid example of an autosomal dominant condition. It may be a condition that is recessive or X-linked, but it does not follow the autosomal dominant pattern.
**Clinical Pearl / High-Yield Fact**
It's worth noting that autosomal dominant conditions can be challenging to diagnose because they can affect any individual, regardless of their family history. A high index of suspicion and a thorough family history are essential in making a diagnosis.
**Correct Answer: D. Marfan Syndrome**