Which of the following condition has autosomal dominant inheritance?
**Core Concept**
Autosomal dominant inheritance is a pattern of genetic inheritance where a single copy of a dominant allele is sufficient to cause the expression of a particular trait or disease. This means that a person can inherit the condition from only one parent, and there is a 50% chance of passing the condition to each offspring.
**Why the Correct Answer is Right**
Autosomal dominant conditions result from mutations in genes that have a crucial role in cellular function. For example, Marfan syndrome is caused by mutations in the **FBN1** gene, which encodes for the protein fibrillin-1. Fibrillin-1 is essential for the formation of elastic fibers found in connective tissue. Mutations in this gene lead to the accumulation of abnormal fibrillin-1, causing the characteristic features of Marfan syndrome, such as tall stature, ectopia lentis, and aortic root dilatation.
**Why Each Wrong Option is Incorrect**
**Option A:** Huntington's disease is an autosomal dominant condition, but it is not among the options provided.
**Option B:** Cystic fibrosis is an autosomal recessive condition, meaning that a person must inherit two copies of the mutated gene (one from each parent) to express the disease.
**Option C:** Duchenne muscular dystrophy is an X-linked recessive condition, primarily affecting boys who inherit the mutated gene from their mothers.
**Option D:** No information is provided for this option, but the question implies that the correct answer is one of the options listed.
**Clinical Pearl / High-Yield Fact**
In autosomal dominant conditions, each offspring of an affected parent has a 50% chance of inheriting the mutated gene, regardless of their sex.
**Correct Answer: C.**