What is Pendred Syndrome?
Pendred syndrome is an inherited disorder that may account for as much as 10% of hereditary congenital hearing impairment. Pendred Syndrome is characterized by a congenital (pre-birth) non-progressive, severe-to-profound sensorineural hearing loss which is frequently coupled with a late childhood or early adult onset of goiter (enlargement of the thyroid gland). Pendred Syndrome is a form of syndromic deafness, which means that there is an additional medical issue in some other area of the body above and beyond the hearing loss.
What causes Pendred Syndrome?
Pendred Syndrome is the result of a mutated gene SLC26A4 (PDS) which is found on the seventh human chromosome (7q31). Normal PDS genes manufacture a protein called pendrin that is found in significant levels only within the thyroid gland. Pendrin transports chloride and iodide ions in and out of thyroid gland cells. When the PDS gene contains a mutation, the normal transportation of chloride and iodine is disrupted, causing Pendred syndrome. Because goiter is not always found in Pendred Syndrome patients, it is possible that a defective PDS gene may be responsible for some cases of deafness that had not previously been attributed to this disorder.
How is Pendred Syndrome transmitted?
Pendred Syndrome is genetically transmitted from parent to child in a recessive manner, which means that an affected individual must inherit one copy of the non-functioning gene from each parent. Carriers who only have one copy of the gene (i.e. one normal gene and one mutated gene) do not manifest any of the signs of the condition, but have a 1 in 2 chance of passing on the defective gene to their children (who would then also be carriers only), and a 1 in 4 chance of having an affected child if the other parent is also a carrier. Pendred Syndrome affects men and woman equally, and does not have any ethnic predisposition.
Because Pendred Sydrome is occasionally associated with Enlarged Vestibular Aqueducts, individuals with Pendred syndrome are typically recommended to avoid contact sports which may lead to head injury and could cause a progression in any existing hearing loss. Head protection precautions should always be used when engaging in activities such as cycling, rollerblading, skateboarding, horseback riding or skiing. Situations that may result in extreme, rapid changes in air pressure, such as hyperbaric oxygen treatment or scuba diving, or flying in small airplanes with unpressurized cabins. Individuals with Pendred Sydrome may wear hearing aids, and if their hearing losses are at the severe to profound level, may qualify as candidates for cochlear implantation.
Who should treat the Condition?
A specialized interdisciplinary team of professionals is necessary to treat all of the issues associated with Pendred Syndrome. This group of individuals should include an Otologist or Otolaryngologists, audiologists, speech-language pathologists, a clinical geneticist and a genetic counselor, as well as an Endocrinologist for monitoring thyroid function. For patients who are children, all of these individuals should have extensive experience in pediatrics.
The California Ear Institute is a leading global center for otological, otolaryngological and audiological treatment. Dr. Joseph Roberson, a board certified neurotologist, has performed thousands of successful hearing related surgeries on children and adults, including many whose hearing impairment is due to Pendred Syndrome.
Consequences of Avoiding Treatment
If it is the desire of the family for their child to hear and speak as normally as possible, it is necessary to seek medical evaluation as soon as possible after birth of a child who is referred by their newborn hearing screening program for additional testing, regardless of whether or not Pendred Syndrome is suspected to be the source of the hearing loss. Delays in treatment for severe to profound sensorineural hearing loss will result in the inability for the patient to develop normal spoken speech and language skills. Additionally, candidacy for cochlear implantation, currently the only medical treatment available for the treatment of profound sensorineural hearing loss, cannot be established without a comprehensive medical examination. Avoiding medical evaluation for a Pendred Syndrome or any other hearing impairment related disorder is not recommended.
Patients searching the internet for information about Pendred Syndrome or any other medical issue should know when reading about individual case histories, that generally it is the patients with the most severe symptoms who either post their own experiences or are included in medical review journals. As a result, it is easy to become overly alarmed and assume the worst. Patients should keep this in mind as they explore the available resources, and look for sources that are certified by HON or other reputable health reviewing organizations. As with all medical conditions, prompt treatment by experienced medical personnel give the best chance for a positive outcome.