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Bardet-Biedl Syndrome

What is Bardet-Biedl Syndrome?

Bardet-Biedl syndrome (BBS) is an inherited condition that impacts multiple parts of the body and is characterized by a wide-range of symptoms including progressive visual impairment, polydactyly (extra fingers or toes), truncal obesity (excessive fat around abdomen), kidney issues, and hypogonadism (insufficient production of hormones in male testes or female ovaries). BBS can be caused by mutations in more than 20 different genes and is typically inherited as an autosomal recessive condition*. There is no cure for BBS, but treatment is available to help manage the specific symptoms and signs that vary across those affected.

 

The condition was once called Laurence-Moon-Biedl-Bardet (LMBB) syndrome following the physicians who described its first cases. Since the condition could only be recognized as a set of symptoms, the syndrome first described by Lawrence and Moon in 1866 was initially considered the same as the one described by George Bardet and Artur Biedl in the early 1920s. However, after further research over the years the syndromes are now recognized as distinct conditions. 

 

*In order to have BBS, a person must have a mutation in both copies of the gene responsible for BBS in each cell. Individuals with BBS inherit one mutated copy of the gene from each parent, so-called carriers. Carriers of autosomal recessive conditions like BBS usually do not experience symptoms and are unaffected. This is called an autosomal recessive inheritance.

 

 

Synonyms

  • Bardet-Biedl Syndrome

Bardet-Biedl syndrome (BBS) is an inherited condition that impacts multiple parts of the body and is characterized by a wide-range of symptoms including progressive visual impairment, polydactyly (extra fingers or toes), truncal obesity (excessive fat around abdomen), kidney issues, and hypogonadism (insufficient production of hormones in male testes or female ovaries). BBS can be caused by mutations in more than 20 different genes and is typically inherited as an autosomal recessive condition*. There is no cure for BBS, but treatment is available to help manage the specific symptoms and signs that vary across those affected.

 

The condition was once called Laurence-Moon-Biedl-Bardet (LMBB) syndrome following the physicians who described its first cases. Since the condition could only be recognized as a set of symptoms, the syndrome first described by Lawrence and Moon in 1866 was initially considered the same as the one described by George Bardet and Artur Biedl in the early 1920s. However, after further research over the years the syndromes are now recognized as distinct conditions. 

 

*In order to have BBS, a person must have a mutation in both copies of the gene responsible for BBS in each cell. Individuals with BBS inherit one mutated copy of the gene from each parent, so-called carriers. Carriers of autosomal recessive conditions like BBS usually do not experience symptoms and are unaffected. This is called an autosomal recessive inheritance.

 

Acknowledgement of Bardet-Biedl Syndrome has not been added yet.

It is estimated that BBS affects around 1 in 250,000 people around the world and affects both males and females equally. The syndrome is more common in certain areas of the world affecting more populations of Newfoundland (1 in 17,500) and the Bedouin population of Kuwait (1 in 13,500). One of the specific gene mutations (BBS10) associated with BBS is particularly common in South Africa.

Name Abbreviation
Bardet-Biedl Syndrome BBS

BBS can be caused by mutations in more than 20 different genes, and it is typically inherited as an autosomal recessive condition. Many of the gene mutations that are known to cause BBS include: BBS1, BBS2, ARL6 (BBS3), BBS4, BBS5, MKKS (BBS6), BBS7, TTC8 (BBS8), BBS9, BBS10, TRIM32 (BBS11), BBS12,MKS1 (BBS13), CEP290 (BBS14), WDPCP (BBS15),SDCCAG8 (BBS16), LZTFL1 (BBS17), BBIP1 (BBS18), IFT27 (BBS19), IFT72 (BBS20), and C8ORF37(BBS21).In spite of the many gene mutations identified above, there are still around 20-30 % of individuals affected by BBS, who have unidentified gene mutations. Certain trends have emerged indicating associations between patients with certain mutations and the specific symptoms of BBS. For example, patients with mutations in the BBS2, BBS3, and BBS4 genes experience classic deterioration of vision, while patients with a BBS10 gene mutation are typically much more prone to obesity and diabetes.Most genes linked to BBS encode proteins that form cilia and basal bodies. Cilia are the tiny hair-like structures that cover different types of cells in the body, and the basal bodies work to anchor the cilia to the cells. Cilia can be motile or immotile. While motile (or moving) cilia work to beat motion, such as keeping nasal airways clear of dirt by moving protective mucus through, domitle (primary) cilia are important signaling hubs passing information from one cell to another, such as determining urine flow in the kidneys. It seems that most gene mutations in BBS generally affect immotile cilia.

The signs and symptoms of BBS vary considerably among affected individuals, even within the same family. Common symptoms and signs include:

Primary characteristics include:

  • Progressive vision loss, which is due to deterioration of the eye’s retina. This typically starts occurring in mid-childhood with problems around night vision and then blind spots in peripheral vision. Most individuals with BBS also develop blurred central vision leading to legal blindness by adolescence or early adulthood (over 90% of cases)

  • Obesity developing around 2-3 years of age

  • Polydactyly (extra fingers or toes)

  • Hypogonadism (reduced hormone production by the testes and ovaries), which in turn can result in infertility 

  • Kidney abnormalities

  • Learning disabilities 

Secondary characteristics include:

  • Delayed development

  • Neurological problems leading to gait and coordination impairment

  • Behavioral disorders

  • High blood pressure

  • Diabetes (specifically type II diabetes in estimately 45% of cases)

  • Heart defects

  • Speech disorders

  • Dental abnormalities including small teeth, small lower jaw, short teeth

  • Flat, wide feet with no arches

  • Thyroid complications

  • Lack of a sense of smell (anosmia)

  • Strabismus or lazy eye

  • Short stature (compared to parents’ height)

  • Toe and finger abnormalities, such as being short; curved (especially outer fingers or toes); mildly webbed (particularly affecting the 2nd and 3rd toes)

An individual is typically diagnosed with BBS if they have four of the primary characteristics (above) or three primary and at least two secondary characteristics (above). Some affected individuals may not have all of the symptoms and signs, and may not receive a clear diagnosis for many years. Healthcare professionals will typically investigate an individuals’ medical history, symptoms, conduct a physical exam and review laboratory test results before making a BBS diagnosis.

Genetic testing can be used to confirm a BBS diagnosis in some individuals with certain gene mutations like BBS1 and BBS10.

As there is no cure for BBS, treatment involves treating the individual’s specific symptoms and consequently the care of multiple healthcare specialists. 

  • For progressive vision loss, there is no specific treatment, but early evaluation can be helpful in determining vision aids and mobility training. Young children should be informed and educated to prepare accordingly for the prospect of future blindness.

  • Obesity and related complications (e.g. diabetes, high blood pressure) can be managed through a combination of education, diet, exercise and behavioral interventions at an early age. 

  • Intellectual disability and speech problems may be managed through early intervention, including special education and speech therapy where needed.

  • Individuals with BBS may require surgery for polydactyly or genital abnormalities. Kidney transplants may also be needed, but the subsequent immunosuppressants after a transplant may increase obesity complications. 

  • In managing hypogonadism, children with BBS approaching puberty should have their hormone levels assessed to determine whether hormone replacement therapy is needed. Adolescents and young adults with BBS should also be advised on contraception, as not all individuals affected by BBS are infertile. 

As BBS symptoms are highly variable across individuals, it can be challenging to predict the course of the disease. More severe symptoms, such as kidney malfunction or obesity complications can lead to early death. However, most individuals with BBS that receive proper treatment and monitoring seem to have a normal or at least near-normal life expectancy. 

Name Description
Tip #1 Exercise can improve the conditions of joints. Exercise such as yoga or Pilates may also help to reduce stress, which can sometimes trigger a flare-up of symptoms. A balanced diet is beneficial to general health. Behçet’s disease is not contagious. When thinking of having a child, discuss plans with a doctor because some of the drugs used as treatment can affect sperm, eggs, fertility, or even the baby. Long-term conditions can affect the mood, emotions, and confidence of the person affected. It can also have an impact on work, social life, and relationships. Talk with a friend, relative, or doctor could help. In addition, contacting support groups is a good way to meet others with Behçet’s disease.

Bardet Biedl Syndrome Foundation. What is BBS? N.d. Available from: https://www.bardetbiedl.org/what-is-bbs#nine 

 

National Organization for Rare Disorders. Bardet-Biedl  Syndrome. 2017. Available from: https://rarediseases.org/rare-diseases/bardet-biedl-syndrome/

 

National Center for Advancing Translational Sciences: Genetic and Rare Diseases Information Center. Bardet-Biedl Syndrome. 2020. Available from: https://rarediseases.info.nih.gov/diseases/6866/bardet-biedl-syndrome

 

Myriad Women’s Health. Bardet-Biedl Syndrome, BBS1-Related. 2020. Available from: https://myriadwomenshealth.com/diseases/bardet-biedl-syndrome-bbs1-related/ 

Community Details Update Created by RareshareTeam
Last updated 11 Nov 2020, 02:39 AM

Posted by RareshareTeam
11 Nov 2020, 02:39 AM

Hi everyone,

The Bardet-Biedl Syndrome community details have been updated. We added more information about the cause, prevalence, symptoms, diagnosis, and treatment. Hopefully, you find it helpful.

 

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CoRDS, or the Coordination of Rare Diseases at Sanford, is based at Sanford Research in Sioux Falls, South Dakota. It provides researchers with a centralized, international patient registry for all rare diseases. This program allows patients and researchers to connect as easily as possible to help advance treatments and cures for rare diseases. The CoRDS team works with patient advocacy groups, individuals and researchers to help in the advancement of research in over 7,000 rare diseases. The registry is free for patients to enroll and researchers to access.

Enrolling is easy.

  1. Complete the screening form.
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  3. Answer the permission and data sharing questions.

After these steps, the enrollment process is complete. All other questions are voluntary. However, these questions are important to patients and their families to create awareness as well as to researchers to study rare diseases. This is why we ask our participants to update their information annually or anytime changes to their information occur.

Researchers can contact CoRDS to determine if the registry contains participants with the rare disease they are researching. If the researcher determines there is a sufficient number of participants or data on the rare disease of interest within the registry, the researcher can apply for access. Upon approval from the CoRDS Scientific Advisory Board, CoRDS staff will reach out to participants on behalf of the researcher. It is then up to the participant to determine if they would like to join the study.

Visit sanfordresearch.org/CoRDS to enroll.

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I am a Pediatrician who has trained in Clinical and Molecular Genetics From the Christian Medical College, Vellore. At present I am working in the Kamalnayan Bajaj Hospital Aurangabad a s a...

I am the mother of a 6 yr old boy who has been recently diagnosed with BBS
I am the parent of a daughter diagnosed with BardetBiedl Syndrome.
Im a Mum with a 3 year old boy with bardet biedl syndrome.

 

Im searching Australia to find others with this in order to gain knowledge to help my son.

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Created by RareshareTeam | Last updated 11 Nov 2020, 02:39 AM


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