Progressive Sensorineural Hearing Loss and a Widened Vestibular Aqueduct in Pendred Syndrome

Abstract

Pendred syndrome is an autosomal recessive inherited disorder. Obligatory features are profound deafness in childhood and defective organic binding of iodine in the thyroid gland. Therefore, goiter is a common symptom. Hypoplasia of the cochlea is another feature. Recently, the gene for Pendred syndrome was identified. We describe a boy whose sensorineural hearing loss in both ears progressed rapidly from about 50 to 60 dB at the age of 3 years and 3 months to more than 100 dB at the age of 4 years and 4 months. This loss was preceded by a medical history of a progressive hearing loss. The progressive nature of the hearing loss motivated a search for the cause. Dysplasia of the cochlea and a widened vestibular aqueduct were found. The results of thyroid function tests were normal, but he had an elevated level of thyroglobulin. The diagnosis of Pendred syndrome was confirmed by the positive results of a potassium perchlorate test, indicating defective organic binding of iodine in the thyroid gland. It is possible that the widened vestibular aqueduct was responsible for the increase in the hearing impairment. Aside from the branchio-otorenal syndrome, Pendred syndrome is the only other known genetic disorder with a widened vestibular aqueduct. If a child has progressive sensorineural deafness and a widened vestibular aqueduct, it is important to consider a diagnosis of Pendred syndrome. A widened vestibular aqueduct may help to elucidate the pathophysiologic characteristics of hearing loss in these genetic types of deafness in childhood.

Mild iodine deficiency is associated with elevated hearing thresholds in children in Benin

“…This would imply multiple lesion sites, including the middle ear, cochlear and retrococlear sites. A number of recent studies have focused on the molecular genetic aspects of auditory defects in patients with resistance to thyroid hormone or with Pendred's syndrome (Leedman, 1996;Brucker Davis et al, 1996;Cremers et al, 1998). Although these defects and congenital hypothyroidism often have deafness and goiter in common, the genetic basis for these syndromes appears to be different (Forrest, 1996).…”

Differential Diagnosis between Pendred and Pseudo-Pendred Syndromes: Clinical, Radiologic, and Molecular Studies

“…It is considered the most common cause of congenital deafness, but the actual incidence of the syndrome is difficult to establish because of the variable phenotype of affected subjects, even within the same family (2)(3)(4). In the last 3 y PS has been associated, with a homozygous or compound heterozygous pattern, to mutations in the PDS gene (5)(6)(7)(8)(9)(10)(11)(12)(13)(14). PDS maps on chromosome band 7q22-31.1 and codes for pendrin (7), a transmembrane protein, which was first found to be expressed in the thyroid and in particular at the apical surface of the thyroid cell, where it likely functions as an iodide-chloride transporter (15)(16)(17).…”

Аналіз Клінічного Випадку Синдрому Пендреда

“…Частота синдро-му Пендреда становить від 1 до 10 % усіх випадків спадкової глухоти. Так, частота синдрому Пендреда на Британських островах становить 7,5 випадку на 100 000 новонароджених [3], у скандинавських краї-нах -близько 1 випадку на 100 000 новонароджених [4]. Опубліковано принаймні 300 випадків синдро-му Пендреда [5].…”

“…Прове-дено аналіз мутацій у гені PDS у 14 сім'ях із синдро-мом Пендреда з 7 країн Європи і виявлено 14 різних мутацій (10 місенс-мутацій, 1 мутація сплайсингу й 3 мікроделеції). Дві з цих мутацій виявилися час-тими: мутація L236P виявлена у 7 сім'ях, а мутація T416P -у 4 сім'ях [4].…”

“…У літературі є повідомлення про незвичайний розподіл пігменту в сітківці у 3 сибсів [4]. Однак інші автори не згадують про подібні зміни.…”