Bardet-Biedl Syndrome

Symptoms

What are the main symptoms of Bardet-Biedl Syndrome?

Main symptoms of Bardet-Biedl syndrome are vision problems (rod-cone dystrophy), obesity (which may cause diabetes mellitus and/or high blood pressure), extra fingers or toes (postaxial polydactyly), cognitive impairment, learning difficulties, reduced size of testes and fertility in males (due to male hypogonadotropic hypogonadism), malformations of females’ genital and urinary organs, and kidney abnormalities. Typically, due to the rod-cone dystrophy, people with Bardet-Biedl syndrome have night blindness which starts around 7-8 years of age; most are legally blind by 15-16 years of age.

Less common and more variable symptoms include impaired speech, delayed motor skills (e.g. walking), behavioral problems, clumsiness (ataxia), ear infections, hearing loss, asthma and partial or complete loss of smell (anosmia). Some individuals have reported issues with the heart, liver, and digestive system.

Specific physical features can include dental (teeth) abnormalities, short fingers and/or toes, wide-spaced eyes, flat nasal (nose) bridge, flared nostrils, a long groove above the center of the lip (philtrum), and downward-slanting eyelid folds (palpebral fissures).

References
  • http://www.ncbi.nlm.nih.gov/books/NBK1363/
  • http://ghr.nlm.nih.gov/condition/bardet-biedl-syndrome
  • http://rarediseases.org/rare-diseases/bardet-biedl-syndrome/
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Are there earlier onset, later onset, or variant forms of Bardet-Biedl Syndrome?

What health problems should I look for in Bardet-Biedl Syndrome?

Any other diseases that look a lot like Bardet-Biedl Syndrome?

Are there one or two characteristic "odd" or "unusual" symptoms or clinical features of Bardet-Biedl Syndrome?

Is there variable expression or incomplete penetrance in Bardet-Biedl Syndrome?

Are there earlier onset, later onset, or variant forms of Bardet-Biedl Syndrome?

Bardet-Biedl syndrome has no specific earlier, later, or variant forms. However, the symptoms of Bardet-Biedl syndrome vary greatly, as does the severity of those symptoms, and even within the same family. Most afflicted with Bardet-Biedl syndrome exhibit vision loss, extra fingers and/or toes, obesity, kidney problems, and learning difficulties. Other symptoms, such as intellectual disability, genital and urinary abnormalities, infertility, speech impairment and behavioral abnormalities, are expressed in different ways—or are not expressed at all—across individuals with Bardet-Biedl syndrome.

References
  • http://rarediseases.org/rare-diseases/bardet-biedl-syndrome/
What health problems should I look for in Bardet-Biedl Syndrome?

The main health problems in people with Bardet-Biedl syndrome are vision loss and poor kidney function. Vision loss is progressive, usually beginning as night blindness around 7-8 years. More than anything else, poor kidney function causes death in people with Bardet-Biedl syndrome, and so should be monitored carefully. Additional health problems include genital and urinary malformation, and hormone-induced obesity and infertility.

References
  • http://www.ncbi.nlm.nih.gov/books/NBK1363/
Any other diseases that look a lot like Bardet-Biedl Syndrome?

Bardet-Biedl syndrome also overlaps with Laurence-Moon syndrome (LMS), so much so that the two were once thought to be the same condition, and were called Laurence-Moon-Bardet-Biedl syndrome (LMBBS). However, differences between the two conditions were noted in the 1980s and each now has its own diagnosis. Nevertheless, some individuals with LMS show genetic mutations in genes related to Bardet-Biedl syndrome, and lines between the conditions remain blurred.

Alstrom syndrome is characterized by vision and hearing abnormalities, childhood obesity, diabetes mellitus and progressive kidney dysfunction. Additional findings may include involuntary eye movements (nystagmus), heart disease, and skin abnormalities. Intelligence is not typically affected and extra fingers and toes are not associated with this condition.

Meckel syndrome (also called Meckel-Gruber syndrome) is characterized by a part of the brain protruding through the front or back of the skull (encephalocele), extra fingers and/or toes, multiple cysts in the kidneys, liver scarring, underdeveloped lungs and genital abnormalities. Mutations in some of the Bardet-Biedl syndrome genes—though not BBS1—have been found in people with Meckel syndrome.

McKusick-Kaufman syndrome (MKKS) is extremely rare and characterized by extra fingers and/or toes, heart defects, water fluid in the uterus and vagina (hydrometrocolpos), genital and urinary malformations, underdeveloped lungs, gastrointestinal abnormalities and kidney problems. The mutation associated with MKKS is called BBS6 and is also associated with Bardet-Biedl syndrome.

Biemond II syndrome is also extremely rare and is characterized by lacking part of the colored portion of the eye (the iris coloboma), intellectual disability, obesity, genital and urinary abnormalities and extra fingers and/or toes. No genes are yet identified with this syndrome.

Prader-Willi syndrome is characterized by low muscle tone (hypotonia), feeding difficulties in infancy, obesity later in life, genital abnormalities, intellectual disability and behavioral problems.

References
  • http://www.ncbi.nlm.nih.gov/books/NBK1363/
  • http://rarediseases.org/rare-diseases/bardet-biedl-syndrome/
Are there one or two characteristic "odd" or "unusual" symptoms or clinical features of Bardet-Biedl Syndrome?

Approximately 70% of people with Bardet-Biedl syndrome have extra fingers and/or toes near their pinkie fingers or pinkie toes (postaxial polydactyly). Vision loss in people with Bardet-Biedl syndrome, while nearly universal, is progressive and may not be present at birth. The extra fingers and/or toes may therefore be the first indication of Bardet-Biedl syndrome.

References
  • http://www.ncbi.nlm.nih.gov/books/NBK1363/
  • http://rarediseases.org/rare-diseases/bardet-biedl-syndrome/
Is there variable expression or incomplete penetrance in Bardet-Biedl Syndrome?

People with Bardet-Biedl syndrome may or may not express all of the symptoms associated with their condition. There is variability, even among family members, regarding both which symptoms are expressed and how severe these symptoms are. The main symptoms, exhibited by most people with Bardet-Biedl syndrome, are vision loss, extra fingers and/or toes, obesity, kidney problems and learning difficulties. However, other symptoms, such as intellectual disability, genital and urinary abnormalities, infertility, speech impairment, and behavioral abnormalities are more variable and may not expressed in an individual with Bardet-Biedl syndrome.

References
  • http://rarediseases.org/rare-diseases/bardet-biedl-syndrome/

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