Okay, let's tackle this question. The question is about Waardenburg syndrome and the gene mutation responsible. First, I need to recall what I know about Waardenburg syndrome. It's a genetic disorder that affects pigmentation and hearing. The key features include pigmentary changes in the hair, skin, and eyes, as well as sensorineural hearing loss. I remember that it's related to the development of neural crest cells, which are important in forming various tissues, including melanocytes and parts of the inner ear.

Now, the question is about the specific gene mutation. I think there are different types of Waardenburg syndrome. Type 1 is associated with mutations in the PAX3 gene, and Type 2 with MITF. Wait, but maybe there are other genes involved too. Let me check. Oh right, another gene is SOX10, which is involved in Type 4. Wait, no, maybe SOX10 is for another type. Let me confirm. I think Type 1 is PAX3, Type 2 is MITF, and Type 4 is EDN3 or EDNRB. Hmm, but the options here are not given, so I need to make sure which is the most common one tested.

Wait, the question says "due to mutation of" without specifying the type. So the answer depends on the most commonly associated gene. Waardenburg syndrome has several types, each with different genes. The most common types are Type 1 and Type 2. Type 1 is PAX3, and Type 2 is MITF. So if the question is general, maybe the answer is PAX3? But the options aren't provided here. The user provided the question with options A-D but without the actual answer choices. However, the correct answer given by the user is missing. Wait, the user included the correct answer as "C. PAX3" but in the question options, it's not listed. Wait, maybe the original question had options with PAX3 as option C. But since the user hasn't provided the options, I need to proceed with the knowledge that the correct answer is PAX3 for Type 1 Waardenburg.

So, the core concept here is the genetic basis of Waardenburg syndrome, specifically the PAX3 gene for Type 1. The mechanism involves the role of PAX3 in neural crest cell migration and differentiation. The wrong options might include other genes like MITF, SOX10, or others. For example, MITF is involved in Type 2, so if an option is MITF, that would be incorrect. The clinical pearl is to remember that PAX3 is for Type 1, which has the characteristic dystopia canthorum (eyes set wide apart), while Type 2 (MITF) doesn't have that feature. The high-yield fact is that PAX3 mutations lead to Type 1, which includes the dystopia canthorum and is autosomal dominant.

**Core Concept**
Waardenburg syndrome is an autosomal dominant disorder caused by mutations in genes critical to neural crest cell development, particularly **PAX3** (Type 1) and **MITF** (Type 2). These genes regulate melanocyte migration and inner ear formation, leading to pigmentary abnormalities and sensorineural hearing loss.

**Why the Correct Answer is Right**

✓ Correct Answer: B. PAX3 gene