Bardet-Biedl syndrome

background

Bardet-Biedl syndrome (BBS) is a rare genetic disorder that affects many areas of the body, primarily the eyes, hands, feet, genitals, and kidneys. In addition, people with BBS tend to be obese, have intellectual disabilities, and be at increased risk of diabetes, high blood pressure, and heart disease. In most people with BBS, visual impairment progresses to legal blindness by about age 16.
BBS overlaps with a condition known as Laurence-Moon syndrome. Controversy still exists as to whether these two syndromes are in fact distinct entities. Ultimately, BBS is distinguished from Laurence-Moon syndrome based on which genes are affected. However, one of the genetic mutations that cause BBS has also been found in individuals with Laurence-Moon syndrome, which illustrates the difficulty in distinguishing the two.
There are 14 types of BBS, each of which is caused by a different genetic mutation. These 14 genes are BBS1, BBS2, ARL6/BBS3, BBS4, BBS5, MKKS/BBS6, BBS7, TTC8/BBS8, B1/BBS9, C12ORF58/BBS10, TRIM/BBS11, C4ORF24/FLJ35630/BBS12, FLJ20345/MKS1, and CEP290. Most people with BBS have mutations in BBS1 or BBS10. These genes provide instructions for making several proteins, many of which are poorly understood.
BBS is usually inherited (passed down among family members) as an autosomal recessive trait. An individual inherits two copies of most genes, one from the mother and one from the father. To inherit an autosomal recessive disorder, an individual must inherit two defective copies of the mutated gene.
The prevalence of BBS in Europe and the United States ranges from one in 100,000 to one in 160,000. Research indicates that the prevalence of BBS is higher among people from Kuwait (about one in 13,500), where parents are frequently consanguineous (closely related). The prevalence in Newfoundland is estimated at about one in 17,500.
There is no known cure for BBS, but treatment focuses on the management of symptoms and prevention of complications.

Related Terms

BBS, Biedl-Bardet syndrome, Laurence-Bardet-Biedl syndrome, Laurence-Moon syndrome (LMS), Laurence-Moon-Bardet-Biedl syndrome (LMBBS), Laurence-Moon-Biedl syndrome.

types of the disease

General: Types of Bardet-Biedl syndrome (BBS) are distinguished by which gene is affected. Symptoms of the various types of BBS are similar except where otherwise indicated below.
Bardet-Biedl syndrome type 1: BBS type 1 is caused by a mutation of the BBS1 gene. This gene has been found to have widespread activity in the body, including in fetal tissues, testes, the retina, and adipose (fat) tissue. The BBS1 gene provides instructions for making the BBS1 protein, the function of which is currently poorly understood. People with BBS type 1 tend to be taller than their parents.
Bardet-Biedl syndrome type 2: BBS2 is caused by a mutation in the BBS2 gene. This gene has widespread activity in the body, including in the brain, kidney, adrenal gland, and thyroid gland. The BBS2 gene provides instructions for making the BBS2 protein, the function of which is currently poorly understood. People with BBS type 2 tend to be shorter than their parents.
Bardet-Biedl syndrome type 3: BBS3 is caused by a mutation of the BBS3 gene, which is also known as the ARL6 gene. The BBS3 gene provides instructions for making the ADP-ribosylation factor-like protein 6. This protein appears to help regulate various cell functions.
Bardet-Biedl syndrome type 4: BBS type 4 is caused by a mutation of the BBS4 gene. The BBS4 gene provides instructions for making the BBS4 protein, which may play a role in insulin resistance and therefore in the development of diabetes. People with BBS type 4 tend to be shorter than their parents.
Bardet-Biedl syndrome type 5: BBS type 5 is caused by a mutation of the BBS5 gene. The BBS5 gene provides instructions for making the BBS protein 5 isoform 2, which is involved in the generation of special cell structures called cilia and flagella.
Bardet-Biedl syndrome type 6: BBS type 6 is caused by a mutation of the BBS6 gene, which is also known as the MKKS gene. This gene is also mutated in a condition known as McKusick-Kaufman syndrome (MKKS). The BBS6 gene provides instructions for making the MKKS/BBS putative chaperonin protein, which has activity in the retina, brain, pancreas, and other organs and may be involved in the development of obesity.
Bardet-Biedl syndrome type 7: BBS type 7 is caused by a mutation of the BBS7 gene. This gene has activity in most of the tissues of the body. The BBS7 gene provides instructions for making the BBS7 protein, the function of which is currently poorly understood.
Bardet-Biedl syndrome type 8: BBS type 8 is caused by a mutation of the BBS8 gene, which is also known as the TTC8 gene. The BBS8 gene provides instructions for making the tetratricopeptide repeat protein 8, the function of which is currently poorly understood but which may be involved in the generation of special cell structures called cilia and flagella.
Bardet-Biedl syndrome type 9: BBS type 9 is caused by a mutation in the BBS9 gene, which is also known as the B1 gene. This gene has activity in many tissues of the body, including the adult heart, skeletal muscle, lungs, liver, kidneys, placenta, and brain. In addition, the BBS9 gene has activity in the fetal kidney, liver, and brain. The BBS9 gene provides instructions for making the parathyroid hormone-responsive B1 protein. The function of this protein is poorly understood, but it may be involved in the eye problems characteristic of BBS.
Bardet-Biedl syndrome type 10: BBS type 10 is caused by a mutation of the BBS10 gene, which is also known as the C12ORF58 gene. The BBS10 gene provides instructions for making the BBS10 protein, the function of which is currently poorly understood.
Bardet-Biedl syndrome type 11: BBS type 11 is caused by a mutation of the BBS11 gene, which is also known as the TRIM32 gene. The BBS11 gene provides instructions for making the tripartite motif protein 32, the function of which is currently poorly understood.
Bardet-Biedl syndrome type 12: BBS type 12 is caused by a mutation of the BBS12 gene, which is also known as the C4ORF24 or FLJ35630 gene. The BBS12 gene provides instructions for making the BBS12 protein. The function of this protein is poorly understood, but it may be involved with the ability of the eye to detect light.
Bardet-Biedl syndrome type 13: BBS type 13 is caused by a mutation of the MKS1 gene, which is also known as the FLJ20345 gene. This gene appears to have activity in the brain, liver, kidneys, and fingers. The MKS1 gene provides instructions for making the MKS1 protein. The function of this protein is poorly understood, but it may play a role in lung development.
Bardet-Biedl syndrome type 14: BBS type 14 is caused by a mutation of the CEP290 gene. This gene provides instructions for making the centrosomal protein, the function of which is currently poorly understood but which may be involved in the generation of special cell structures called cilia.