Bardet-Biedl syndrome (BBS) is a rare, relatively unfamiliar genetic intellectual and developmental disability (IDD). If a loved one has been diagnosed with it, or if you’ve newly met someone who has it—whether he or she is a family member, friend or part of a friend’s family, co-worker, neighbor, or someone else—you certainly wouldn’t be alone in realizing you don’t know much about it. So, here’s some introductory information about Bardet-Biedl syndrome to help you understand it better.
Basic Facts About Bardet-Biedl Syndrome
- BBS is rare; throughout most of North America and Europe, it affects 1 in 140,000 to 160,000 newborns. Globally, it affects about 1 in 250,000 people.
- This IDD affects males and females in equal numbers.
- Mutations in at least 14 to 20 different genes (sometime referred to as “BBS genes”) can cause Bardet-Biedl syndrome.
- BBS is usually inherited in an autosomal recessive pattern. There are mutations in both copies of a BBS gene in each cell. Both of the affected person’s parents carry one copy of the mutated gene, but typically don’t have any signs or symptoms of the condition.
- The severity of Bardet-Biedl syndrome varies greatly, even among members of the same family.
- Vision loss is a hallmark symptom of Bardet-Biedl syndrome, caused by gradually deteriorating retinas.
- Typically, problems first develop with night vision in mid-childhood, then blind spots develop in the peripheral vision. As the condition progresses, the blind spots get bigger, resulting in tunnel vision. Next, the central vision usually becomes blurry, and an individual with Bardet-Biedl syndrome generally meets the criteria for being considered legally blind by the later teenage years or early adulthood.
- Abnormal weight gain (especially concentrated disproportionately in the abdomen) and obesity is another classic symptom, typically beginning within the first one to three years and lasting throughout the person’s life. Complications of being overweight, such as high blood pressure, high cholesterol, and type 2 diabetes, are common as well.
- Many people with Bardet-Biedl syndrome have extra fingers and/or toes. They may also have genital abnormalities (especially males) like testicular hypogonadism, and are frequently infertile, as well as serious to potentially life-threatening structural kidney defects and other renal problems. Heart and liver defects are also seen sometimes, though less often than kidney problems.
- Some combination of intellectual impairment, learning disabilities, impaired speech, delayed motor development, poor coordination, and behavioral problems—all of varying severity—is also usually seen in people with this IDD.
- There’s no cure for the vision problems associated with BBS, but ongoing care from an ophthalmologist can help manage some aspects.
- Weight management techniques like an active lifestyle and healthy eating are important for people with Bardet-Biedl syndrome. Any weight-related complications like hypertension, high cholesterol, or diabetes are treated as they are among the general population.
- Surgery is commonly used to address physical abnormalities seen in BBS patients, such as extra digits and kidney defects.
- Various therapies can help with many of the intellectual and learning disabilities and the speech and behavioral problems caused by BBS. Early intervention can be very beneficial.
- This intellectual and developmental disability was first called Laurence-Moon-Biedl-Bardet syndrome, after the four physicians who first described it. However, Laurence-Moon syndrome and BBS are now considered two different conditions.