Bardet-Biedl Syndromes

Clinical Characteristics
Ocular Features: 

The term Bardet-Biedl is applied to a clinically and genetically diverse group of disorders, of which at least 21 entities (BBS1-BBS21) are recognized.  This discussion is generically relevant to all of the phenotypes since the retinal dystrophy is common to all.

A progressive rod-cone dystrophy is a cardinal feature of all forms of Bardet-Biedl syndrome.  However, a subset of patients have primary cone degeneration.  In at least some forms of this syndrome, the cause seems to be a defect in the cilia that impairs the intraciliary protein transport between the inner and outer segments of the photoreceptors.  Vision loss has an early onset and usually progresses rapidly with severe loss of central and peripheral vision by the second or third decade of life.  Night blindness may be evident by 7 or 8 years of age.  The ERG is not recordable even in early childhood.  Pigmentary changes in the retina are often labeled retinitis pigmentosa but they are atypical for the usual disease.  Early changes are more characteristic of atrophy with a paucity of pigment but later the bone spicule pattern of hyperpigmentation appears.  The macula can appear atrophic and sometimes has a bull's eye pattern.  Optic atrophy and retinal arteriole narrowing may be seen.  Bardet-Biedl syndrome is clinically similar to Biemond syndrome (210350) except for iris colobomas that occur in the latter disorder.

Systemic Features: 

Obesity, mental retardation, renal disease, and hepatic fibrosis with syndactyly, brachydactyly, and post-axial polydactyly are characteristic.  The degree of mental handicap varies widely.  Diabetes mellitus is present in about one-third of patients.  Structural deformities of genitalia as well as hypogonadism and menstrual irregularities often occur as in some other disorders but the association of severe vision loss and characteristic retinal changes are diagnostically helpful.  Kidney failure secondary to cystic nephronophthisis or other renal malformations is common. Hypercholesterolemia is found in many patients.  Many patients have motor difficulties, appearing clumsy and unsteady.  Emotional lability and inappropriate outbursts can be part of these syndromes as well.


The syndromes of Bardet-Biedl are inherited in an autosomal recessive pattern.  At least 21 mutations have been identified.  Not all cases are caused by homozygosity of the same mutation since compound heterozygosity at two loci may also cause similar phenotypes.

Laurence-Moon syndrome (245800) is considered part of the Bardet-Biedl group of diseases in this database. 

Mutations in PNPLA6 have been found in some individuals with a form of Bardet-Biedl syndrome as well as in Boucher-Neuhauser Syndrome (215470) also known as Chorioretinopathy, Ataxia, Hypogonadism Syndrome, and Trichomegaly Plus Syndrome (275400), in this database.

Autosomal recessive
Treatment Options: 

No treatment exists for these syndromes but organ specific therapy may be helpful.

Studies in a mice model suggest that the neural retina may at least partially recover in type 1 following subretinal injection of viral vectors containing the wild-type bbs1 gene.


Article Title: 

Bardet-Biedl Syndrome

Suspitsin EN, Imyanitov EN. Bardet-Biedl Syndrome. Mol Syndromol. 2016 May;7(2):62-71.

PubMed ID: 

Predominantly cone-system dysfunction as rare form of retinal degeneration in patients with molecularly confirmed Bardet-Biedl Syndrome

Scheidecker S, Hull S, Perdomo Y, Studer F, Pelletier V, Muller J, Stoetzel C, Schaefer E, Defoort-Dhellemmes S, Drumare I, Holder Graham E, Hamel Christian P, Webster Andrew R, Moore Anthony T, Puech B, Dollfus Helene J. Predominantly cone-system dysfunction as rare form of retinal degeneration in patients with molecularly confirmed Bardet-Biedl Syndrome. Am J Ophthalmol. 2015 May 14. [Epub ahead of print]. 

PubMed ID: 

Neuropathy target esterase impairments cause Oliver-McFarlane and Laurence-Moon syndromes

Hufnagel RB, Arno G, Hein ND, Hersheson J, Prasad M, Anderson Y, Krueger LA, Gregory LC, Stoetzel C, Jaworek TJ, Hull S, Li A, Plagnol V, Willen CM, Morgan TM, Prows CA, Hegde RS, Riazuddin S, Grabowski GA, Richardson RJ, Dieterich K, Huang T, Revesz T, Martinez-Barbera JP, Sisk RA, Jefferies C, Houlden H, Dattani MT, Fink JK, Dollfus H, Moore AT, Ahmed ZM. Neuropathy target esterase impairments cause Oliver-McFarlane and Laurence-Moon syndromes. J Med Genet. 2015 Feb;52(2):85-94.

PubMed ID: 

Mutations in IFT172 Cause Isolated Retinal Degeneration and Bardet-Biedl Syndrome

Bujakowska KM, Zhang Q, Siemiatkowska AM, Liu Q, Place E, Falk MJ, Consugar M, Lancelot ME, Antonio A, Lonjou C, Carpentier W, Mohand-Sayid S, den Hollander AI, Cremers FP, Leroy BP, Gai X, Sahel JA, van den Born LI, Collin RW, Zeitz C, Audo I, Pierce EA. Mutations in IFT172 Cause Isolated Retinal Degeneration and Bardet-Biedl Syndrome. Hum Mol Genet. 2014 Aug 28.  [Epub ahead of print].

PubMed ID: 
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