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 Bardet-Biedl Syndrome (BBS)

What causes Bardet-Biedl syndrome?
How is Bardet-Biedl treated?

Bardet-Biedl syndrome is a rare genetic disorder that affects the brain and can cause multiple physical problems including a deterioration of the intellect and neurological functions. The syndrome sometimes affects eyesight with a condition called rod-cone dystrophy, a degeneration of light-sensitive cells in the periphery of the retina. This eye disorder causes night blindness, tunnel vision, decreased visual acuity, and photophobia (extreme sensitivity of the eyes to light). Other symptoms of Bardet-Biedl syndrome may include extra toes and/or fingers, mental retardation, kidney disease, and obesity.

What causes Bardet-Biedl syndrome?

Bardet-Biedl syndrome is characterized as recessively inherited. In other words, neither parent exhibits characteristics of the disorder, but both carry the recessive gene that causes the disorder. Parents who have one affected child run a 25 percent chance in each additional pregnancy of the condition occurring again. There is also a two in three chance that children of subsequent pregnancies, although not affected, will be carriers of the recessive gene. The syndrome is rare because the recessive gene is only carried by approximately 1 in 179 people. Therefore, a person carrying the gene is unlikely to conceive children with another person who also carries the gene.

How is Bardet-Beidl treated?

Bardet-Biedl syndrome can be difficult to diagnose, especially in the young, because many of the symptoms are not yet obvious and may vary considerably from one patient to another. Because there is no known cure, physicians concentrate on the treatment of specific organs and systems.

Most victims of Bardet-Biedl syndrome experience progressive retinal degeneration, with night blindness usually appearing by age 9 and legal blindness often occurring by age 15. Other visual symptoms may include nystagmus (involuntary eye movement), nearsightedness, strabismus (cross-eye), glaucoma, and cataracts.

There is no known treatment for the progressive vision problems that often occur in persons with Bardet-Biedl syndrome. However, there is much that can be done to prepare for a life with low vision. An ophthalmologist should be consulted to accurately diagnose the specific problems, and other vision professionals, including low vision specialists, can assist in making life easier for sufferers.

Some of the other common characteristics of Bardet-Biedl syndrome are:

  • Extra fingers or toes, ranging from a single skin tag to a fully formed digit
  • Short, stubby fingers and/or toes, more frequently in the feet than in the hands
  • Webbing of toes
  • A high frequency of obesity, usually beginning at 1 or 2 years of age
  • Learning difficulties
  • Small testes and genitalia in men

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