Pendred syndrome

Pendred syndrome is a pathology characterized by bilateral sensorineural hearing loss and thyroid goiter with or without hypothyroidism.

Most patients with Pendred syndrome have homozygous or compound heterozygous mutations in the SLC26A4 gene that codes for pendrin, a protein expressed in the inner ear, thyroid, kidney and bronchial epithelial cells. Pendrin acts by facilitating the transport of iodine, chloride and bicarbonate into the cells.

Pendred's syndrome accounts for up to 10% of all cases of congenital hearing loss and its prevalence is estimated at 1-9 cases per 100,000 population. Therefore, this syndrome is the most frequent cause of syndromic deafness.

Sensory hearing impairment, usually bilateral, is present in all patients with Pendred syndrome and usually appears before the child develops speech and language. In rare cases it develops progressively in childhood. This deficiency manifests with the absence of reaction to sounds or a delay in language development. Malformations of the inner ear such as an enlarged vestibular aqueduct and cochlear hypoplasia occur.

Thyroid enlargement is present in more than half of the cases and usually progresses between childhood and adolescence leading to multinodular goiter. However, the development of goiter is highly variable, even in affected members of the same family, and depends, in part, on nutritional intake of iodine.

The management of Pendred's syndrome focuses on alleviating symptoms. Pendred's patients need to be followed by a multidisciplinary team to evaluate hearing problems (sometimes cochlear implants are needed, which are devices that stimulate the auditory nerve), monitor thyroid function (in some cases pharmacological treatment or surgery is required) and offer genetic counseling.