Pendred syndrome can affect the thyroid by causing it to grow too large. An enlarged thyroid gland also is called a goiter. The thyroid is a small, butterfly-shaped gland in the front of your neck, just above your collarbones. The thyroid plays a major role in how your body uses energy from food. In children, the thyroid is important for normal growth and development. Children with Pendred syndrome, however, rarely have problems growing and developing properly even if their thyroid is affected.

Roughly 60 percent of individuals with Pendred syndrome will develop a goiter in their lifetime. Most people with Pendred syndrome are in their teens or twenties before they develop a goiter. If a goiter becomes large, a person may have problems breathing and swallowing. A health professional is needed to check a person’s goiter over time and decide what treatment is necessary.

Pendred syndrome also may affect the vestibular system, which controls balance. About 40 percent of individuals with Pendred syndrome will show some vestibular weakness when their balance system is tested. However, the brain is very good at making up for a weak vestibular system, and most children and adults with Pendred syndrome do not have a problem with their balance or have difficulty doing routine tasks. Some babies with Pendred syndrome may start walking later than other babies.

It is not known why some individuals with Pendred syndrome develop a goiter or have balance problems and others do not.