Which of the following is autosomal dominant in inheritance?
## Core Concept
The question tests understanding of genetic inheritance patterns, specifically focusing on autosomal dominant conditions. Autosomal dominant inheritance refers to a pattern where a single copy of a dominant allele is enough to cause the condition. This means if one parent has the condition, each child has a 50% chance of inheriting the mutated gene.
## Why the Correct Answer is Right
The correct answer, , is associated with an autosomal dominant pattern of inheritance. This condition is characterized by its dominant expression, meaning only one copy of the mutated gene is necessary for the individual to express the condition. The underlying genetic mechanism involves mutations in specific genes that lead to the production of abnormal proteins or a lack of essential proteins, resulting in the condition's phenotype.
## Why Each Wrong Option is Incorrect
- **Option A:** is typically associated with an autosomal recessive pattern of inheritance. This means an individual must inherit two copies of the mutated gene (one from each parent) to express the condition.
- **Option B:** follows an X-linked recessive pattern. Conditions with this inheritance pattern are more common in males, who have only one X chromosome. Females would need to inherit two copies of the mutated gene (one on each X chromosome) to express the condition.
- **Option C:** is inherited in an autosomal recessive manner. Individuals with this condition have two copies of the mutated gene, and it often presents with severe symptoms.
## Clinical Pearl / High-Yield Fact
A key point to remember is that autosomal dominant conditions often have a family history, with each child of an affected parent having a 50% chance of inheriting the condition. This pattern can sometimes skip generations if the condition is not fully penetrant or if there are multiple genetic and environmental factors at play.
## Correct Answer Line
**Correct Answer: D. **