Pendred syndrome is an inherited disorder leading to bilateral sensorineural hearing loss. Children who are born with Pendred syndrome may begin to lose their hearing at birth or by the time they are three years old. Usually, their hearing will worsen over time. The loss of hearing often happens suddenly, although some individuals will later regain some hearing. Eventually, some children with Pendred syndrome become totally deaf. Other abnormalities of the inner ear are also common in Pendred syndrome. Some affected individuals have problems with balance caused by dysfunction of the part of the inner ear that helps maintain the body's balance and orientation. By late childhood through adulthood, some individuals develop a goiter, which is an enlargement of the thyroid gland. In most cases, this enlargement does not cause the thyroid gland to malfunction. Intellect is not affected in individuals with Pendred Syndrome. Pendred syndrome is caused by pathogenic variants in the SLC26A4 gene.