Characteristics of hearing loss in HDR (hypoparathyroidism, sensorineural deafness, renal dysplasia) syndrome.

Haploinsufficiency of the zinc finger transcription factor GATA3 causes the triad of hypoparathyroidism, deafness and renal dysplasia, known by its acronym HDR syndrome. The purpose of the current study was to describe in detail the auditory phenotype in human HDR patients and compare these to audiometrical and histological data previously described in a mouse model of this disease. Pure tone audiometry, speech audiometry, speech in noise, auditory brainstem responses and transiently evoked otoacoustic emissions were measured in 2 patients affected by HDR syndrome. Both patients were affected by a moderate-to-severe sensorineural hearing loss. Speech reception thresholds were shifted and speech recognition in noise was disturbed. No otoacoustic emissions could be generated in either patient. Auditory brainstem response interpeak intervals were normal. The human and murine audiological phenotypes seem to correspond well. Hearing loss in HDR syndrome is moderate to severe, seems to be slightly worse at the higher end of the frequency spectrum and may be progressive with age. The absence of otoacoustic emissions and the loss of frequency selectivity suggest an important role for outer hair cells in causing the hearing loss.