Histopathological findings suggest the diagnosis in an atypical case of Pendred syndrome

Radiological malformation of the labyrinth, specifically dilatation of the vestibular aqueduct, has been clearly established as a feature in the major ity of patients with Pendred syndrome. Mutations of the Pendred syndrome (P DN) gene have been identified in this autosomal recessive form of deafness. There is no direct correlation between the nature of the underlying mutati on and the clinical features of deafness, thyroid dysfunction and cochlear malformation. We report a family, the proband of which was thought to deafn ess secondary to congenital hypothyroidism. At autopsy, histopathological e xamination of this patient revealed a dilated vestibular aqueduct. Subseque nt work on the family has confirmed the diagnosis of Pendred syndrome in th e proband and her affected sister.