Pendred syndrome / nonsyndromic enlarged vestibular aqueduct (PDS/NSEVA) comprises a phenotypic spectrum of sensorineural hearing loss (SNHL) that is usually congenital and often severe to profound (although mild-to-moderate progressive hearing impairment also occurs), vestibular dysfunction, and temporal bone abnormalities (bilateral enlarged vestibular aqueduct with or without cochlear hypoplasia). PDS also includes development of euthyroid goiter in late childhood to early adulthood whereas NSEVA does not.

Branchiootorenal spectrum disorder (BORSD) is characterized by malformations of the outer, middle, and inner ear associated with conductive, sensorineural, or mixed hearing impairment, branchial fistulae and cysts, and renal malformations ranging from mild renal hypoplasia to bilateral renal agenesis. Some individuals progress to end-stage renal disease (ESRD) later in life. Extreme variability can be observed in the presence, severity, and type of branchial arch, otologic, audiologic, and renal abnormality from right side to left side in an affected individual and also among individuals in the same family.