When a functional gene is inherited from one parent only, the condition is known as
## Core Concept
The question pertains to the concept of genomic imprinting, a phenomenon where the expression of a gene depends on its parental origin. This is a crucial aspect of genetics, particularly in understanding certain genetic disorders.
## Why the Correct Answer is Right
The correct answer, **Imprinting**, refers to a process where a gene's expression is determined by its parental origin. When a functional gene is inherited from one parent only, and its expression is dependent on the parental origin, it is an example of genomic imprinting. This occurs because certain genes are epigenetically modified (imprinted) during gametogenesis, leading to their expression or silencing based on whether they come from the mother or the father.
## Why Each Wrong Option is Incorrect
- **Option A:** This option is blank and does not provide any information to evaluate.
- **Option B:** This option is also blank and cannot be assessed.
- **Option C:** Similarly, this option is blank and lacks relevant information for evaluation.
- **Option D:** This option is blank as well.
## Clinical Pearl / High-Yield Fact
A classic example of genomic imprinting is **Prader-Willi syndrome** and **Angelman syndrome**. Prader-Willi syndrome occurs when there's a deletion on chromosome 15 inherited from the father or when there are two maternal copies of chromosome 15 (maternal uniparental disomy). Angelman syndrome occurs when there's a deletion on chromosome 15 inherited from the mother or when there are two paternal copies of chromosome 15. This highlights the importance of parental origin in gene expression.
## Correct Answer Line
**Correct Answer: D. Imprinting**