About branchio-oto-renal dysplasia
What is branchio-oto-renal dysplasia?
Branchio-oto-renal (BOR) syndrome is a rare disorder inherited as an autosomal dominant genetic trait. This disorder is characterized by pits or ear tags in front of the outer ear, abnormal passages from the throat to the outside surface of the neck (branchial fistulas), branchial cysts, hearing loss and/or kidney (renal) abnormalities.
What are the symptoms for branchio-oto-renal dysplasia?
Most people with BOR/BOS syndrome have some type of hearing loss. The Hearing loss may be due to nerve damage (sensory), blockage of sound waves (conductive), or both. The degree of Hearing loss varies from mild to profound, and can differ between the two ears. The deafness can be stable or progressive. Other abnormalities related to the ear that may be present include pits or outgrowths of cartilage (tags) in front of the outer ear; a cupped or small outer ear; and/or a narrow or upward slanted outer ear canal.
An abnormal passage from the throat to the outside surface of the neck (branchial fistula), and/or an opening on the side of the neck, or a mass that can be felt under the muscles on the side of the neck is often present.
The Kidney abnormalities associated with BOR syndrome range from mild to very severe. In milder cases, the kidney may be unusually shaped. In more severe cases, there may be duplication of the collecting system of the kidneys and/or absence or failure of one or both of the kidneys to form.
Other abnormalities that have been found in association with BOR syndrome are narrowing of the tear duct in the eyes interfering with the normal flow of tears; a long narrow face; cleft palate; Paralysis of certain muscles in the face; and/or a deep overbite.
What are the causes for branchio-oto-renal dysplasia?
BOR/BOS syndrome is caused by mutations in the EYA1(BOR1, BOS2), SIX5 (BOR2), and SIX1 (BOR3, BOS3) genes.
BOR/BOS syndrome is inherited as an autosomal dominant disorder. Dominant genetic disorders occur when one copy of a gene is abnormal and this abnormal copy results in the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy. The risk is the same for males and females.
What are the treatments for branchio-oto-renal dysplasia?
The child with hearing impairment should undergo appropriate rehabilitation measures with annual hearing testing (audiometry). Medical attention should be sought promptly for any episode of inflammation of the middle ear (otitis media).
Patients with BOR/BOS syndrome may benefit from hearing aids. When structural defects of the ear are present, surgery may be beneficial.
Branchial cleft deformities have the potential to become easily infected and may require surgical treatment such as excision of the branchial cleft cyst or fistulae. Antibiotics can be given if the cyst or sinuses are infected. Also, a physician specializing in kidney problems (nephrologist) should closely monitor any renal impairment. Surgical repair may be undertaken for correctable defects. Severe kidney problems may warrant dialysis or kidney transplantation.
Semiannual examination for hearing impairment is recommended to assess stability of hearing loss. Semiannual examination for renal function is recommended to prevent progression of worsening of the kidneys.
Genetic counseling is recommended for patients and their families. Other treatment is symptomatic and supportive.
What are the risk factors for branchio-oto-renal dysplasia?
BOR/BOS syndrome affects males and females in equal numbers. It is estimated that 1 in 40,000 people have this disorder. BOR/BOS syndrome is found in approximately 2 to 3 percent of children with profound deafness.