**Question:** Feature of Autosomal dominant disorder:

A. Inheritance pattern is followed by both sons and daughters
B. Symptoms appear in early childhood
C. Disease is caused by a mutation in a single gene
D. Disease is not seen in females who are carriers

**Correct Answer:** A. Inheritance pattern is followed by both sons and daughters

**Core Concept:** Autosomal dominant disorders are a type of inheritance pattern where the disease-causing gene is located on an autosome (non-sex chromosomes) and the affected individual must inherit the mutated gene from at least one affected parent. In autosomal dominant disorders, the offspring has a 50% chance of inheriting the mutated gene regardless of sex.

**Why the Correct Answer is Right:**
Autosomal dominant disorders result from a single gene mutation. When an individual inherits a mutated gene from one affected parent, they become a carrier. In this case, the offspring inherit the gene from the carrier parent, leading to a 50% chance of inheriting the mutated gene, regardless of their sex (male or female). This means that the inheritance pattern is followed by both sons and daughters, making option A the correct answer.

**Why Each Wrong Option is Incorrect:**

- Option B: Symptoms appearing in early childhood does not specifically relate to the inheritance pattern of autosomal dominant disorders. While some autosomal dominant disorders may manifest early, the focus here is on the inheritance pattern, not the disease presentation.
- Option C: Mentioning "a mutation in a single gene" is an oversimplification of autosomal dominant disorders, as it does not fully capture the complexity of inheritance patterns. The focus is on the inheritance pattern, not the genetic basis.
- Option D: Disease is not seen in females who are carriers is incorrect because carriers do not necessarily exhibit symptoms. Autosomal dominant disorders can affect both males and females, leading to a 50% chance of inheriting the mutated gene from their carrier parent. Female carriers can also pass on the mutated gene to their offspring.

**Clinical Pearl:**

Autosomal dominant disorders can be challenging to diagnose as they often manifest in a milder form or not at all in carriers. It is essential for healthcare providers to consider inheritance patterns when evaluating patients with suspected genetic disorders, particularly when dealing with families with multiple affected individuals.