Progressive hearing loss, hypoplasia of the cochlea and widened vestibular aqueducts are very common features in Pendred’s syndrome

Molecular Genetics of Vestibular Organ Development

“…Widened vestibular aqueducts are commonly found in the inner ears of these patients. In addition, cochleae of Mondini phenotype characterized by incomplete coiling have also been described (Johnsen et al 1986;Cremers et al 1998). …”

Loss of cochlear HCO3−secretion causes deafness via endolymphatic acidification and inhibition of Ca2+reabsorption in a Pendred syndrome mouse model

“…Childhood deafness, postpuberty goiter, and an enlarged endolymphatic duct are the hallmarks of Pendred syndrome (12,28,30,32). Although deafness is generally profound, it is variable and sometimes late in onset (6,41). Studies of Pendred syndrome have recently been facilitated by the development of an animal model (Slc26a4 Ϫ/Ϫ mice) and pendrin-specific polyclonal antibodies (9,33).…”

“…Pendred syndrome can be associated with deafness at birth or with progressive hearing loss during childhood (6,41). This implies that hearing develops in at least some cases but is lost during childhood.…”

Developmental delays consistent with cochlear hypothyroidism contribute to failure to develop hearing in mice lacking Slc26a4/pendrin expression

“…Hearing loss can be congenital or progressive during childhood (14,16). This implies that a reduction or lack of pendrin function is compatible with hearing, but that this deficiency facilitates hearing loss in conjunction with other genetic and/or epigenetic factors.…”