Okay, I need to create a detailed explanation for the MCQ about Pendred Syndrome. Let me start by recalling what Pendred Syndrome is. It's a genetic disorder that causes hearing loss and thyroid problems, right? The key features are sensorineural hearing loss and goiter. Now, the question is asking which statement is true about Pendred Syndrome. The correct answer is probably related to the SLC26A4 gene mutation causing both the hearing loss and the thyroid issues.

First, the core concept here is the autosomal recessive inheritance pattern. The SLC26A4 gene is involved in ion transport, affecting both the inner ear and the thyroid. The gene codes for a protein called pendrin, which is crucial for the development of the cochlea and the function of the thyroid gland. So the core concept is the genetic mutation leading to both auditory and thyroid manifestations.

Next, why the correct answer is right. The correct answer would state that Pendred Syndrome is associated with a mutation in the SLC26A4 gene. This mutation leads to defects in pendrin, which is expressed in the cochlea and thyroid. The inner ear fluid homeostasis is disrupted, causing hearing loss, and the thyroid can't regulate iodine properly, leading to goiter. This is the main pathophysiology. Also, the syndrome is autosomal recessive, so the correct answer might mention that.

Now, the wrong options. Let's think about common misconceptions. One might confuse Pendred with other syndromes. For example, some might think it's caused by a different gene like GJB2, which is for non-syndromic hearing loss. Another wrong option could be that it's X-linked, but it's actually autosomal recessive. Another possible wrong answer is that it's associated with renal issues, but Pendred is mainly about hearing and thyroid. Also, some might think the goiter is non-toxic, but in Pendred, it's usually euthyroid goiter.

Clinical pearl: Remember that Pendred Syndrome is the most common cause of syndromic hearing loss with goiter. The SLC26A4 mutation is key here, and it's autosomal recessive. Also, the presence of a large vestibular aqueduct is a radiological finding associated with Pendred Syndrome. So, in exams, if a question links hearing loss and goiter, think Pendred and SLC26A4.

Putting it all together, the correct answer would be the one mentioning SLC26A4 gene mutation. The other options would be incorrect for the reasons mentioned. I need to structure the explanation with the required sections, making sure each part is concise and covers the necessary points without exceeding the character limit.

**Core Concept**
Pendred syndrome is an **autosomal recessive** disorder caused by mutations in the **SLC26A4** gene, which encodes the **pendrin** protein. This protein is critical for **ion transport** in the **cochlea** (affecting hearing) and **thyroid gland** (causing goiter). The syndrome is characterized by **sensorineural hearing loss**, **euthyroid goiter**, and **vestibular aqueduct enlargement** on imaging.

**Why the Correct Answer is Right**
The correct answer highlights the **SLC26A4 gene mutation

✓ Correct Answer: D. All