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Background: The syndrome of Bardet-Biedl is definite clinically by the association of obesity, polydactyly, pigmentary retinopathy, hypogonadism and backwardness., Aim: To study the epidemiologic, clinical, biological, genetic, therapeutic and evolutionary characteristic of our patients., Methods: We carried out a retrospective study concerning 11 hospitalized children and/or follow-ups with the service of pediatry of the CHU Hédi Chaker of Sfax for syndrome of Bardet-Biedl during a period of 21 years (1987-2007)., Results: The obesity was constant among all patients, polydactyly was found in 9 cases, the fall of night vision in 7 cases. The hypogonadism was constant among all our boys. The bottom of eye was practised among 9 patients, it showed a pigmentary aspect of retinopathy among 8 patients. The electroretinogram was done in 10 patients, it showed a pigmentary retinopathy in all the cases. The radiological exploration of the urinary tract made it possible to identify morphological anomalies in 3 cases. The genetic study concerned the families of one of our patients and it allowed the identification of a new gene BBS8 at one of the families. Treatment was only symptomatic. After 6 years an average retreat, we noted an aggravation of obesity (9cas) and visual deficit (7cas). Only one patient evolved to the chronic renal insufficiency., Conclusion: The syndrome of Bardet-Biedl is a hereditary disease characterized by a genetic heterogeneity. The diversity of the systemic attacks defining this syndrome is a source of several handicaps: blindness, backwardness and obesity. The forecast is conditioned by the renal attack of or the interest of an early tracking and genetic council.

Bardet-Biedl syndrome (BBS) is a ciliopathy causing multivisceral abnormalities. Its prevalence in Europe is from 1/125,000 to 1/175,000. This disorder is defined by a combination of clinical signs: obesity, pigmentary retinopathy, post-axial polydactyly, polycystic kidneys, hypogenitalism, and learning disabilities, many of which appearing after several years of evolution. Individual clinical phenotype is highly variable. Most signs are present in a majority of patients but only pigmentary retinopathy is constant after infancy. There are many other associated minor clinical signs including diabetes, blood hypertension, congenital cardiopathy or Hirschsprung disease. This broad clinical spectrum is associated to a great genetic heterogeneity, with mainly an autosomal recessive transmission and, sometimes cases of oligogenism. To date, mutations in 12 different genes (BBS1 to BBS12) are responsible for this phenotype. These genes code for proteins involved in the development and function of primary cilia. Absent or non functional BBS proteins affect cilia in certain organs such as kidney or eye. However, some symptoms are still not clearly related to cilia dysfunction. BB syndrome has to be recognized because a molecular diagnosis is possible and will lead to familial genetic counseling and possibly prenatal diagnosis. Patients with BBS will need a multidisciplinary medical care. The renal abnormalities are the main life-threatening features because they can lead to end-stage renal failure and renal transplantation. Retinal dystrophy leading to progressive vision loss, moderate mental retardation, and obesity will affect social life of these patients.

Obesity has become an increasingly prevalent public health problem and results of the complex interaction of genetic and environmental factors. The study of rare syndromic forms of obesity enables progress in identifying molecular and physiological mechanisms, underlying the development of adiposity, food intake and energy expenditure. The identified role of the hypothalamic leptin-melanocortin pathway as major in monogenic forms of obesity, has led to the recognition of new genes controlling energy homeostasis and new pharmacological targets.

Until recently, Bardet-Biedl syndrome was considered as a classic autosomal recessive condition. The disorder is defined by the association of the following clinical features: retinitis pigmentosa, polydactyly, obesity, hypogonadism, and possible mental retardation. This syndrome leads to multiple handicaps (visual impairment, complications of obesity, kidney failure, endocrine dysfunction). This condition, apparently clearly defined from a clinical point of view, appears to be genetically heterogenous. To date, six different genes have been identified: BBS1, BBS2, BBS4, BBS6, BBS7 and BBS8. Interestingly, this condition has recently been linked to a failure of cellular ciliogenesis. Moreover, this disorder is characterized by an additional degree of complexity, as it is the first example of triallelic inheritance described in human beings. However, this new finding appears to be less frequent than expected in this syndrome.

Laurence-Moon syndrome, which is very rare, and Bardet-Biedl syndrome, which is more frequent are now well-recognized as two distinct entities in pediatric neurology. Bardet-Biedl syndrome includes a number of common clinical signs it shares with Laurence-Moon syndrome but also with other syndromes, particularly Alströme syndrome. These signs are retinitis pigmentosa, mental retardation, obesity, and hypogonadism. Ophthalmological and electrophysiological examinations are essential for confirmation and correct diagnosis of Bardet-Biedl syndrome. We present three case histories. Our third case illustrates the possibility of below normal yet discernable electroretinogram amplitudes which do not infirm the diagnosis of Bardet-Biedl syndrome.