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Branchiootorenal Spectrum Disorders.


Smith RJH1.


GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2018.
1999 Mar 19 [updated 2015 Oct 22].

Author information

Director, Molecular Otolaryngology and Renal Research Laboratories, Sterba Hearing Research Professor of Otolaryngology, Professor of Otolaryngology, Pediatrics, and Internal Medicine, Division of Nephrology, Carver College of Medicine, University of Iowa, Iowa City, Iowa



Branchiootorenal spectrum disorders comprise branchiootorenal (BOR) syndrome and branchiootic syndrome (BOS). BOR 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. BOS has the same features as BOR syndrome but without renal involvement. 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. BOR syndrome and BOS can be seen in the same family.


The diagnosis of branchiootorenal spectrum disorders is based on clinical criteria. Molecular genetic testing of EYA1 (BOR1, BOS1) detects pathogenic variants in approximately 40% of individuals with the clinical diagnosis of BOR/BOS. Pathogenic variants can be detected in an additional 5% and 4% of individuals with the clinical diagnosis of BOR/BOS by molecular genetic testing of SIX5 (BOR2) and SIX1 (BOR3, BOS3), respectively.


Treatment of manifestations: Excision of branchial cleft cysts/fistulae, fitting with appropriate aural habilitation, and enrollment in appropriate educational programs for the hearing impaired are appropriate. A canaloplasty should be considered to correct an atretic external auditory canal. Medical and surgical treatment for vesicoureteral reflux may be necessary. End-stage renal disease (ESRD) may require dialysis or renal transplantation. Surveillance: Semiannual examination for hearing impairment and annual audiometry to assess stability of hearing loss; monitoring of renal function to prevent progression to ESRD; semiannual/annual examination by a nephrologist and/or urologist, as indicated. Agents/circumstances to avoid: Nephrotoxic medications. Evaluation of relatives at risk: At-risk relatives should be screened for hearing loss and renal involvement to allow for early diagnosis and treatment.


BOR syndrome and BOS are inherited in an autosomal dominant manner. The offspring of an affected individual are at a 50% risk of inheriting the pathogenic variant. Prenatal testing for pregnancies at risk is possible if the pathogenic variant has been identified in a family member.

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