Branchio-oto-renal syndrome

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Branchio-oto-renal syndrome
Other namesBOR syndrome, Branchiootorenal syndrome
Branchio-oto-renal syndrome has an autosomal dominant pattern of inheritance.
SpecialtyMedical genetics Edit this on Wikidata
SymptomsEar abnormalities[1]
CausesMutations in genes, EYA1, SIX1, and SIX5[2]
Diagnostic methodLaboratory test results, Physical exam[3]
TreatmentBranchial fistula may need surgery[3]

Branchio-oto-renal syndrome (BOR)[4][5] is an autosomal dominant genetic disorder involving the kidneys, ears, and neck. It is also known as Melnick-Fraser syndrome.[2][3]

Signs and symptoms[edit]

The signs and symptoms of branchio-oto-renal syndrome are consistent with underdeveloped (hypoplastic) or absent kidneys with resultant chronic kidney disease or kidney failure. Ear anomalies include extra openings in front of the ears, extra pieces of skin in front of the ears (preauricular tags), or further malformation or absence of the outer ear (pinna). Malformation or absence of the middle ear is also possible, individuals can have mild to profound hearing loss. People with BOR may also have cysts or fistulae along the sides of their neck.[1] In some individuals and families, renal features are completely absent. The disease may then be termed "branchio-oto syndrome" (BO syndrome).[6][7]


The cause of branchio-oto-renal syndrome are mutations in genes, EYA1, SIX1, and SIX5 (approximately 40 percent of those born with this condition have a mutation in the EYA1 gene).[1][8] Many different abnormalities in these genes have been identified.[9]


The genetics of branchio-oto-renal syndrome indicate it is inherited in an autosomal dominant manner with variable clinical manifestations affecting branchial, renal, and auditory development. Autosomal dominant inheritance indicates that the defective gene responsible for a disorder is located on an autosome, and only one copy of the gene is sufficient to cause the disorder, when inherited from a parent who has the disorder. The varying clinical expression of the disease between different families suggests that multiple loci may be involved. In 1992, using genetic linkage studies, the BOR gene was identified on chromosome 8,[10] Subsequently, another locus on human chromosome 14 was identified, and several mutations were reported in genes EYA1, SIX1,[11] and SIX5.[12][13] SINX1 is involved in many facets of embryonic development and is important in the normal formation of many organs and tissues, including the ears, and kidneys before birth.[14]


Diagnosis of BO syndrome or BOR syndrome is clinical, i.e. based on observing an appropriate combination of symptoms.[6] Only about half of patients have a detectable genetic abnormality, mostly in the EYA1 gene, SIX1 gene or the SIX5 gene.[6]


Otitis media -acute

The treatment of branchio-oto-renal syndrome is done per each affected area (or organ). For example, a person with hearing problems should have appropriate supports and prompt attention for any inflammation of the ear.[6][15]

A specialist should observe any kidney problems. Surgical repair may be needed depending on the degree of a defect or problem, whether a transplant or dialysis is needed.[16]


The epidemiology of branchio-oto-renal syndrome has it with a prevalence of 1/40,000 in Western countries. A 2014 review found 250 such cases in the country of Japan.[17]

See also[edit]


  1. ^ a b c "Branchio Oto Renal Syndrome". NORD (National Organization for Rare Disorders). Archived from the original on 2020-09-26. Retrieved 2015-11-29.
  2. ^ a b "Branchiootorenal syndrome". Genetics Home Reference. U.S. National Library of Medicine. 2015-11-23. Archived from the original on 2016-02-29. Retrieved 2015-11-29.
  3. ^ a b c "Branchiootorenal syndrome | Disease | Overview". Genetic and Rare Diseases Information Center (GARD) – an NCATS Program. Archived from the original on 2016-07-27. Retrieved 2015-11-29.
  4. ^ Kumar S (2004). "Branchio-oto-renal Syndrome". In Willems PJ (ed.). Genetic Hearing Loss. New York: Marcel Dekker Inc. doi:10.1201/9780203913062. ISBN 9780203913062. Archived from the original on 2022-11-13. Retrieved 2022-11-13.
  5. ^ Kumar S, Deffenbacher K, Cremers CW, Van Camp G, Kimberling WJ (1997). "Branchio-oto-renal syndrome: identification of novel mutations, molecular characterization, mutation distribution, and prospects for genetic testing". Genetic Testing. 1 (4): 243–251. doi:10.1089/gte.1997.1.243. PMID 10464653.
  6. ^ a b c d Smith RJ (1993-01-01). "Branchiootorenal Spectrum Disorder". In Pagon RA, Adam MP, Ardinger HH, Wallace SE, Amemiya A, Bean LJ, et al. (eds.). Branchiootorenal Spectrum Disorders. Seattle (WA): University of Washington, Seattle. PMID 20301554. Archived from the original on 2021-03-09. Retrieved 2017-08-30.|updated, 2015|
  7. ^ Kumar S, Marres HA, Cremers CW, Kimberling WJ (April 1998). "Autosomal-dominant branchio-otic (BO) syndrome is not allelic to the branchio-oto-renal (BOR) gene at 8q13". American Journal of Medical Genetics. 76 (5): 395–401. doi:10.1002/(sici)1096-8628(19980413)76:5<395::aid-ajmg6>;2-m. PMID 9556298.
  8. ^ Little MH (2015-08-06). Kidney Development, Disease, Repair and Regeneration. Academic Press. p. 269. ISBN 9780128004388.
  9. ^ Smith RJ (1993). Adam MP, Everman DB, Mirzaa GM, Pagon RA (eds.). Branchiootorenal Spectrum Disorder. Seattle (WA): University of Washington, Seattle. PMID 20301554
  10. ^ Kumar S, Kimberling WJ, Kenyon JB, Smith RJ, Marres HA, Cremers CW (October 1992). "Autosomal dominant branchio-oto-renal syndrome--localization of a disease gene to chromosome 8q by linkage in a Dutch family". Human Molecular Genetics. 1 (7): 491–495. doi:10.1093/hmg/1.7.491. PMID 1307249.
  11. ^ Ruf RG, Xu PX, Silvius D, Otto EA, Beekmann F, Muerb UT, et al. (May 2004). "SIX1 mutations cause branchio-oto-renal syndrome by disruption of EYA1-SIX1-DNA complexes". Proceedings of the National Academy of Sciences of the United States of America. 101 (21): 8090–8095. Bibcode:2004PNAS..101.8090R. doi:10.1073/pnas.0308475101. PMC 419562. PMID 15141091.
  12. ^ Krug P, Morinière V, Marlin S, Koubi V, Gabriel HD, Colin E, et al. (February 2011). "Mutation screening of the EYA1, SIX1, and SIX5 genes in a large cohort of patients harboring branchio-oto-renal syndrome calls into question the pathogenic role of SIX5 mutations" (PDF). Human Mutation. 32 (2): 183–190. doi:10.1002/humu.21402. PMID 21280147. S2CID 25826641. Archived (PDF) from the original on 2022-11-13. Retrieved 2022-11-13.
  13. ^ Online Mendelian Inheritance in Man (OMIM): Branchiootorenal Syndrome 1; BOR1 - 113650
  14. ^ Mehdizadeh T, Majumdar HD, Ahsan S, Tavares AL, Moody SA (June 2021). "Mutations in SIX1 Associated with Branchio-oto-Renal Syndrome (BOR) Differentially Affect Otic Expression of Putative Target Genes". Journal of Developmental Biology. 9 (3): 25. doi:10.3390/jdb9030025. PMC 8293042. PMID 34208995.
  15. ^ Niparko JK (2009-01-01). Cochlear Implants: Principles & Practices. Lippincott Williams & Wilkins. p. 53. ISBN 9780781777490. Archived from the original on 2023-01-12. Retrieved 2020-11-25.
  16. ^ Izzedine H, Tankere F, Launay-Vacher V, Deray G (February 2004). "Ear and kidney syndromes: molecular versus clinical approach". Kidney International. 65 (2): 369–385. doi:10.1111/j.1523-1755.2004.00390.x. PMID 14717907.
  17. ^ Morisada N, Nozu K, Iijima K (June 2014). "Branchio-oto-renal syndrome: comprehensive review based on nationwide surveillance in Japan". Pediatrics International. 56 (3): 309–314. doi:10.1111/ped.12357. PMID 24730701. S2CID 40930806.

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