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Bardet-Biedl syndrome


Other Names for this Disease

  • BBS
  • Biedl-Bardet Syndrome
  • Laurence Moon Bardet Biedl syndrome
  • Laurence Moon syndrome
  • LMBBS
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Overview

What is Bardet-Biedl syndrome?

What are the signs and symptoms of Bardet-Biedl syndrome?

How is Bardet-Biedl syndrome inherited?

How might Bardet-Biedl syndrome be treated?

What is Bardet-Biedl syndrome?

Bardet-Biedl syndrome is an inherited condition that affects many parts of the body. People with this condition have progressive visual impairment due to cone-rod dystrophy, extra fingers or toes (polydactyly), truncal obesity, decreased function of the male gonads (hypogonadism), kidney abnormalities, and learning difficulties.[1] At least 14 genes are known to be associated with Bardet-Biedl syndrome.[2] This condition is usually inherited in an autosomal recessive pattern.[2]
Last updated: 6/27/2014

What are the signs and symptoms of Bardet-Biedl syndrome?

Bardet-Biedl syndrome (BBS) affects many parts of the body, and signs and symptoms of the condition can vary among affected individuals. One of the major features of BBS is progressive vision loss due to deterioration of the retina. Typically, this begins in mid-childhood with problems with night vision and is followed by the development of blind spots in the peripheral vision. These blind spots become bigger with time and eventually merge to produce tunnel vision. Most individuals also develop blurred central vision and become legally blind by adolescence or early adulthood.[3]

Other major signs and symptoms of BBS include obesity (which can cause type 2 diabetes, high blood pressure, and abnormally high cholesterol levels); kidney abnormalities; the presence of extra fingers and/or toes (polydactyly); intellectual disability or learning problems; and abnormalities of the genitalia. Most affected males are infertile because they produce reduced amounts of sex hormones. Other characteristics of the condition may include impaired speech; delayed development of motor skills; behavioral problems; and poor coordination. Additional features that have been reported in some people with BBS include distinctive facial features; dental abnormalities; unusually short or fused fingers and/or toes; a partial or complete loss of the sense of smell (anosmia); and other abnormalities.[3]
Last updated: 10/3/2011

How is Bardet-Biedl syndrome inherited?

Bardet-Biedl syndrome has an autosomal recessive pattern of inheritance.[2] People with this syndrome have mutations in both copies of a gene associated with Bardet-Biedl syndrome. These people typically have unaffected parents who each carry a single copy of the mutated gene (and are referred to as carriers). When two carriers of an autosomal recessive condition have children, each child has a 25% (1 in 4) risk to have the condition, a 50% (1 in 2) risk to be a carrier, and a 25% chance to not have the condition and not be a carrier (i.e. have 2 normal copies of the gene). An affected individual's full siblings who do not have Bardet-Biedl syndrome have approximately a 66 % (2/3) chance of being a carrier for the condition. Autosomal recessive disorders are typically not seen in every generation of an affected family.
Last updated: 6/27/2014

How might Bardet-Biedl syndrome be treated?

There is no cure for Bardet-Biedl syndrome. Treatment generally focuses on the specific signs and symptoms that each individual has. Although there is no therapy for the progressive vision loss, early evaluation by a specialist can help to provide vision aids and mobility training. Furthermore, the education of affected children should include planning for future blindness. The management of obesity may include education, diet, exercise, and behavioral therapies beginning at an early age. Complications of obesity, such as abnormally high cholesterol and diabetes mellitus, are usually treated as they are in the general population. Management of intellectual disability includes early intervention, special education and speech therapy as needed. Many affected adults are able to develop independent living skills.

Although kidney transplants have been successful, the immunosuppressants used after a transplant may contribute to obesity. Affected individuals may undergo surgical correction of polydactyly (extra fingers and/or toes) and genital abnormalities. As children approach puberty, hormone levels should be monitored to determine if hormone replacement therapy is necessary. Additionally, it should not be assumed that affected individuals are infertile so contraception advice should be offered.[4]
Last updated: 10/24/2012

References
  1. Bardet Biedl Syndrome. National Organization for Rare Disorders. 2007; http://www.rarediseases.org/rare-disease-information/rare-diseases/byID/988/viewAbstract. Accessed 6/27/2014.
  2. Forsythe E, Beales PL. Bardet-Biedl Syndrome. GeneReviews. February 20, 2014; http://www.ncbi.nlm.nih.gov/books/NBK1363/. Accessed 6/27/2014.
  3. Bardet-Biedl syndrome. Genetics Home Reference. May 2010; http://ghr.nlm.nih.gov/condition/bardet-biedl-syndrome. Accessed 10/3/2011.
  4. Aoife M Waters, Philip L Beales. Bardet-Biedl syndrome. GeneReviews. September 29, 2011; http://www.ncbi.nlm.nih.gov/books/NBK1363/. Accessed 10/3/2011.


Other Names for this Disease
  • BBS
  • Biedl-Bardet Syndrome
  • Laurence Moon Bardet Biedl syndrome
  • Laurence Moon syndrome
  • LMBBS
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.