What is Bardet-Biedl syndrome, BBS10-related?

Bardet-Biedl syndrome (BBS), BBS10-related, is an inherited disease that causes a variety of symptoms including vision problems, obesity, extra fingers or toes (polydactyly), genital and kidney problems, and learning difficulties. The condition is caused by harmful genetic changes (variants) in the BBS10 gene.

A hallmark of BBS is vision loss caused by retina degeneration (rod-cone dystrophy). It begins as night blindness in childhood and progresses to a loss of peripheral vision. Individuals with BBS can also lose central vision during childhood or adolescence. The mean age at which individuals become legally blind is 15.5 years. By early adulthood, affected individuals are severely visually impaired.

Kidney problems are present in most individuals with BBS and can range from a few functional problems to life-threatening kidney failure. Many affected individuals have developmental disabilities. This can range from mild learning disabilities or delayed emotional development to more severe symptoms. In some individuals, these delays are partly due to vision loss, while in other cases, they directly result from the disease.

Rarer features include liver disease, diabetes, neurological issues such as poor balance and coordination, behavioral issues, characteristic physical features, high blood pressure, defects of the heart or reproductive system, and hearing loss. These features vary between individuals.

More than 20 genes are associated with BBS, some associated with other syndromes such as Laurence-Moon syndrome, retinitis pigmentosa, and Meckel-Gruber syndrome. It is unclear if these represent a spectrum of diseases or if BBS is distinct from the other associated syndromes. A few reports identified harmful changes in the BBS10 in individuals with Meckel-like syndrome, which has features that include kidney disease, extra fingers or toes, and brain malformations.

How common is Bardet-Biedl syndrome, BBS10-related?

Harmful changes in the BBS10 gene account for approximately 15% of BBS cases. The number of individuals affected with BBS ranges from 1 in 100,000 to 1 in 160,000. BBS is more common in Kuwaiti Bedouins (1 in 13,500) and individuals from Newfoundland (1 in 17,500). It is also reported to be more common in individuals from South Africa.

How is Bardet-Biedl syndrome, BBS10-related, treated?

There is no cure for BBS. A team of specialists must manage the associated symptoms. A geneticist is typically involved in diagnosing and managing an affected child. Treatment may include monitoring, provision of aids and therapies, or surgery. Patients are recommended to undergo regular monitoring of vision, weight, and blood pressure, as well as thyroid, kidney, and liver function. An ophthalmologist will manage vision issues; vision aids can help improve quality of life. The FDA has approved at least one medication, setmelanotide (Imcivree), for the treatment of obesity in individuals with BBS. Medications can help treat high blood pressure. An endocrinologist may be consulted for diabetes, thyroid disease, and proper pubertal development. Kidney issues are managed in a standard fashion, but if they become life-threatening, dialysis or transplantation may be necessary. Surgery can correct some birth defects (extra digits may be removed in childhood, or heart and vaginal malformation may be corrected), and an orthodontist may assist with correction of dental anomalies. Early intervention and therapies may assist with learning difficulties.

What is the prognosis for an individual with Bardet-Biedl Syndrome, BBS10-related?

Predicting symptoms and the course of the disease for individuals with BBS can be difficult due to the variable nature of the condition, even within families. One of the most consistent features is progressive vision loss, frequently leading to blindness. Kidney disease is also frequent and is a cause of early death for individuals with BBS. Complications of obesity, heart disease, and diabetes have also been reported as causes of early death. However, with treatment, many individuals have a normal or near-normal life expectancy with some impairments.

Other names for
Bardet-Biedl syndrome, BBS10-related

  • BBS
  • BBS10-related Bardet-Biedl syndrome
  • Bardet-Biedl syndrome 10

References

  • Forsythe et al., 2023, http://www.ncbi.nlm.nih.gov/books/NBK1363/
  • Khan et al., 2016, Clin Genet, 90(1):3-15, PMID: 26762677
  • M’hamdi et al., 2014, Mol Syndromol, 5(2):51-6, PMID: 24715851
  • Suspitsin et al., 2016, Mol Syndromol, 7(2):62-71, PMID: 27385962
  • Álvarez-Satta et al., 2017, Front Mol Biosci, 4:55, PMID: 28824921