Chances of an offspring being affected when one parent is autosomal dominant heterozygote?
## **Core Concept**
The question tests understanding of autosomal dominant inheritance patterns in genetics. Autosomal dominant conditions occur when a single copy of the dominant allele is enough to cause the condition. The heterozygous state of one parent implies they have one normal allele and one disease-causing allele.
## **Why the Correct Answer is Right**
In autosomal dominant conditions, each child has a 50% chance of inheriting the mutated gene from a heterozygous parent. This is because the heterozygous parent can pass either the normal allele or the disease-causing allele to each offspring. The chance of an offspring being affected (expressing the condition) is thus 50%, as they only need to inherit one copy of the dominant allele to express the condition.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option suggests a 0% chance, which is incorrect because there's a chance the offspring can inherit the mutated gene.
- **Option B:** This option suggests a 25% chance, which applies to autosomal recessive conditions when both parents are carriers, not to autosomal dominant conditions.
- **Option D:** This option suggests a 100% chance, which is incorrect because the offspring have a chance of inheriting the normal allele from the heterozygous parent.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that in autosomal dominant disorders, **affected individuals have a 50% chance of passing the mutated gene to each offspring**. This pattern often results in the condition appearing in every generation of a family.
## **Correct Answer:** . 50%