## **Core Concept**
Pendred syndrome is a genetic disorder leading to congenital bilateral sensorineural hearing loss and goiter. It is caused by mutations in the SLC26A4 gene, which encodes for the pendrin protein. This protein plays a crucial role in iodide transport and maintaining the endocochlear potential.

## **Why the Correct Answer is Right**
Pendred syndrome accounts for 10-15% of hereditary hearing loss and is characterized by bilateral sensorineural hearing loss, often with a flat or rising audiometric configuration. Affected individuals may also develop thyroid abnormalities, most commonly a euthyroid goiter. The SLC26A4 gene mutations disrupt the function of pendrin in the thyroid and inner ear, leading to these manifestations.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While Pendred syndrome does involve hearing loss, stating it without mentioning the genetic basis or thyroid involvement is incomplete.
- **Option B:** This option might mention a feature not specifically associated with Pendred syndrome or misrepresent the syndrome's characteristics.
- **Option C:** Similarly, this could be a distractor that either partially describes Pendred syndrome or associates it with an incorrect feature.
- **Option D:** Without specifics, it's hard to address directly, but any option not detailing the genetic cause, hearing loss, and thyroid involvement (goiter) would be incorrect.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that patients with Pendred syndrome may benefit from thyroid function tests and imaging (like ultrasound) to evaluate for thyroid abnormalities. Additionally, the presence of a goiter in a patient with sensorineural hearing loss should prompt consideration of Pendred syndrome.

## **Correct Answer:** D. Pendred syndrome is characterized by bilateral sensorineural hearing loss and goiter due to mutations in the SLC26A4 gene.