Branchio-Oto-Renal (BOR) Syndrome
(Source: Boystown Research Registry)
Branchio Oto Renal Syndrome (BOR) is a genetic disorder that includes malformations of the ear and cysts in the neck, hearing loss, and malformations of the kidney. BOR has an autosomal dominant mode of inheritance. This means that for an individual who has BOR, there is a 50% chance of passing on the gene with each pregnancy. Nonpenetrance (having no sign or symptom of the disorder despite having the gene) is very unusual for BOR. However, variable expression (variation in the manner and severity with which the gene is expressed among and within families) is very common, and an individual with the gene may have only one or two of the three clinical aspects of the syndrome.
The B in BOR refers to the branchial arches which is the area of the embryo that develops into the outer and middle ear, the neck and the lower part of the baby´s face. There are several types of malformations of the branchial arches in BOR including cupping of the outer ear, ear pits which are very small holes (about the size of the hole in a pierced ear) in front of or on the outer ear, tags of skin in front of the ear, and cysts or fistulas on the neck.
Oto refers to the ear and in particular the hearing loss that is part of the syndrome. The hearing loss can be sensorineural, conductive or mixed. It can be stable or progressive and the severity can range from mild to profound. Most people with BOR have some degree of hearing loss.
Renal refers to the kidneys which can be abnormal in size, shape and/or structure. They may be smaller than usual or have a malformation that does not interfere with function or cause any symptoms. However, the kidney malformation may be severe enough to predispose the individual to kidney disease, or a baby may be born without kidneys which would be incompatible with life. Most people with BOR do not experience any type of kidney problem.
In some families with BOR there are individuals who have blocked tear ducts which interfere with the normal flow of tears and have to be opened surgically. There have also been reports of individuals with salivary tissue in their tear ducts which causes them to have tearing when they eat.
The BOR gene has been mapped to chromosome 8. Research continues to actually identify the gene. It is hoped that eventually we will be able to determine how the gene causes the problems associated with BOR which may lead to treatment or prevention of the progression of those problems.
Smith, R. J. H., et al.
(1992) Localization of the gene for branchiootorenal syndrome to chromosome 8q. Genomics 14: 841-844.
Kumar, S., et al.
(1992) Autosomal dominant branchio-oto-renal syndrome--localization of a disease gene to chromosome 8q by linkage in a Dutch family. Hum. Molec. Genet. 1: 491-495.
Date Originally Created: Winter of 1989.
The information presented here first appeared in publications of the Boys Town National Research Register for Hereditary Hearing Loss, the National Institute on Deafness and Other Communication Disorders (NIDCD), Hereditary Hearing Impairment Resource Registry (HHIRR), or the Boys Town Research Registry for Hereditary Hearing Loss.
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The Boys Town Research Registry for Hereditary Hearing Loss (Registry) is designed to foster a partnership between families, clinicians and researchers in the area of hereditary hearing loss/deafness through three primary functions. First, the Registry disseminates information to professionals and families about clinical and research issues related to hereditary deafness/hearing loss. Second, the Registry collects information from individuals interested in supporting and participating in research projects. This information is used to support the third function of the Registry - matching families with collaborating research projects.
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