In a family, the father has widely spaced eyes, medial eyebrow flare and deafness. One of the three children has deafness with similar facial features. The mother is normal. Which one of the following is most likely pattern of inheritance in this case?
**Core Concept**
The underlying principle being tested is the identification of a genetic disorder based on its clinical presentation and pattern of inheritance, specifically focusing on **Waardenburg syndrome**, which is characterized by **dystopia canthorum** (widely spaced eyes), **medial eyebrow flare**, and **sensorineural deafness**.
**Why the Correct Answer is Right**
Given the father and one of the children exhibit similar facial features and deafness, and assuming the correct answer choice is related to an autosomal dominant pattern, this would explain the vertical transmission of the disorder from parent to offspring. **Waardenburg syndrome** is known to be inherited in an **autosomal dominant** manner, meaning a single copy of the mutated gene is sufficient to cause the condition.
**Why Each Wrong Option is Incorrect**
**Option A:** This choice would be incorrect if it suggested an autosomal recessive pattern, as this would require both parents to be carriers and would not typically result in a parent and child both being affected.
**Option B:** If this choice represented an X-linked pattern, it would not fit the scenario since the father is affected and could not pass an X-linked disorder to his sons.
**Option C:** If representing a mitochondrial inheritance pattern, it would not apply as the disorder described does not exclusively follow maternal lineage.
**Why Each Wrong Option is Incorrect (Continued)**
**Option D:** Assuming this is not the correct choice, if it were to represent a pattern that does not align with the observed family history, such as sporadic or an incorrect mode of inheritance, it would be incorrect.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that **Waardenburg syndrome** is a disorder that affects the development of the ear, eye, and skin, and its **autosomal dominant** inheritance pattern means that each child of an affected parent has a 50% chance of inheriting the condition.
**Correct Answer:** Correct Answer: D. Autosomal Dominant.