Bardet-Biedl syndrome (BBS) clinically presents with retinal degeneration, limb abnormalities (polydactyly, brachydactyly), obesity (hyperphagia), developmental delay, reproductive anomalies and renal/ urinary tract abnormalities that may lead to renal failure as cardinal features. There is a broad spectrum of additional clinical symptoms accompanying the above mentioned features (e.g. neurological abnormalities, hearing problems, dental anomalies, cardiac anomalies and diabetes mellitus) that are reported in some patients with BBS. The reported prevalence of BBS varies considerably regionally between 1:13500 (Kuwait, Newfoundland) and 1:160000 (northern Europe population) [1;2].

BBS is a mostly autosomal recessive inherited genetic disease. 18 BBS genes are know so far, most of the genes encode for proteins in the basal body of primary ciliae [3]. Additional modifiers are reported in several cases, that addtionally complicate the path of heredity. [4-7].

Primary cilia have a broad tissue distribution and are present on most cell types in the human body. Originally considered to be redundant, research over the past years describe them as evolutionarily conserved organelles, that play an decisive role in mammalian development. They are located at cell surfaces and play a significant role in whole-cell locomotion; movement of fluid; chemo-, mechano-, and photosensation; and sexual reproduction. Defects in cilia are associated with a range of human diseases, such as primary ciliary dyskinesia, hydrocephalus, polycystic liver and kidney disease, and retinal degeneration.

Epidemiologic studies on BBS including a high number of patients are rare, mostly emphasizing on adults with BBS. Knowledge about childhood, especially in the first years of life, is rudimentary, more frequently presented in small-scale cases. Apart from observing the occurrence and development of main cardinal features of BBS information about growth, onset of puberty, psychomotor development is not observed systematically.

 

known genes for BBS

 

Sources