Chances of an offspring being affected when one parent is autosomal dominant heterozygote ?
**Core Concept**
Autosomal dominant disorders follow a simple pattern of inheritance where a single copy of the mutated gene is enough to cause the condition. This means that an individual with one mutated allele and one normal allele (heterozygous) will express the disease.
**Why the Correct Answer is Right**
When one parent is an autosomal dominant heterozygote, each offspring has a 50% chance of inheriting the mutated allele. This is because the law of segregation states that each allele has an equal chance of being passed on to the offspring. Therefore, the offspring can be either homozygous dominant (affected) or homozygous recessive (unaffected), each with a 50% probability. In this case, the offspring has a 50% chance of being affected.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the probability of inheritance is not 0% (the offspring has a chance of inheriting the mutated allele).
**Option B:** This option is incorrect because the probability of inheritance is not 100% (the offspring can also inherit the normal allele).
**Option C:** This option is incorrect because it is not a valid probability (the sum of probabilities of all possible outcomes in a random experiment must be 1 or 100%).
**Clinical Pearl / High-Yield Fact**
In autosomal dominant disorders, the presence of a single mutated allele is enough to cause the condition, making it more likely for the offspring to be affected compared to autosomal recessive disorders where two mutated alleles are required.
**Correct Answer: C. 50%**