When a functional gene is inherited from one parent only, the condition is known as –
**Core Concept**
When a functional gene is inherited from one parent only, it leads to a condition where the individual has only one functional allele of the gene, while the other allele is either non-functional or absent. This scenario is a classic example of a monogenic disorder, where a mutation in a single gene causes the disease.
**Why the Correct Answer is Right**
In this scenario, the individual is said to be heterozygous for the mutated gene, meaning they have two different alleles - one normal and one mutated. This heterozygosity can lead to a variety of outcomes, including incomplete penetrance and variable expressivity. The affected gene can be inherited from either parent, but the fact that it's only inherited from one parent means the individual is not homozygous for the mutation.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the scenario described in the question.
**Option B:** This option is incorrect because it's not the correct term for inheriting a functional gene from one parent only.
**Option C:** This option is incorrect because it's not the correct term for the condition described in the question.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that heterozygosity for a mutated gene can lead to a range of clinical outcomes, from asymptomatic to severe disease. Understanding the genetic basis of monogenic disorders is crucial for diagnosing and managing these conditions.
**Correct Answer:** C. Uniparental Disomy.