Children who are born with PS may begin to lose their hearing at birth or by the time they are three years old. The hearing loss is progressive, which means that a child will have less hearing over time and quite often is bilateral (meaning it affects both of the ears). Some individuals may become totally deaf (see entry Deafness). PS can affect the thyroid (a small gland in the front of the neck) by causing it to grow too large. An enlarged thyroid gland is known as a goiter.
Learning difficulties may occur in individuals with PS due to congenital thyroid defects. In a few rare cases, this may also increase the risk of thyroid cancer (see entry Cancer). PS also may affect the vestibular system, which controls balance and some individuals with PS will show some vestibular weakness when their balance system is tested.