ABSTRACT
Bardet-Biedl syndrome (BBS) is an autosomal recessive multisystemic human genetic disorder characterized by six major defects including obesity, mental retardation, renal anomalies, polydactyly, retinal degeneration and hypogenitalism. In several cases of BBS, few other features such as metabolic defects, cardiovascular anomalies, speech deficits, hearing loss, hypertension, hepatic defects and high incidence of diabetes mellitus have been reported as well. The BBS displays extensive genetic heterogeneity. To date, 19 genes have been mapped on different chromosomes causing BBS phenotypes having varied mutational load of each BBS gene. In this review, we have discussed clinical spectrum and genetics of BBS. This report presents a concise overview of the current knowledge on clinical data and its molecular genetics progress upto date.
Subject(s)
Bardet-Biedl Syndrome/diagnosis , Bardet-Biedl Syndrome/genetics , Genetic Heterogeneity , Microtubule-Associated Proteins/genetics , Mutation , Bardet-Biedl Syndrome/classification , Bardet-Biedl Syndrome/pathology , Diabetes Mellitus/diagnosis , Diabetes Mellitus/genetics , Diabetes Mellitus/pathology , Female , Gene Expression , Humans , Intellectual Disability/diagnosis , Intellectual Disability/genetics , Intellectual Disability/pathology , Male , Multigene Family , Obesity/diagnosis , Obesity/genetics , Obesity/pathology , Pedigree , Phenotype , Polydactyly/diagnosis , Polydactyly/genetics , Polydactyly/pathology , Protein Isoforms/genetics , Retinal Degeneration/diagnosis , Retinal Degeneration/genetics , Retinal Degeneration/pathologyABSTRACT
Bardet-Biedl syndrome (BBS) is a ciliopathy characterized by retinal degeneration, obesity, polydactyly, renal abnormalities, and cognitive impairment for which 15 causative genes have been identified. Here we present the results of a mutational analysis of our multiethnic cohort of 83 families (105 cases); 75.9% of them have their mutations identified including 26 novel changes. Comprehensive phenotyping of these patients demonstrate that the spectrum of clinical features is greater than expected and overlapped with the features of other ciliopathies; specifically Alström and McKusick-Kauffman syndromes.
Subject(s)
Bardet-Biedl Syndrome/classification , Bardet-Biedl Syndrome/diagnosis , Mutation/genetics , Abnormalities, Multiple/diagnosis , Abnormalities, Multiple/genetics , Abnormalities, Multiple/pathology , Adolescent , Adult , Alstrom Syndrome/diagnosis , Alstrom Syndrome/genetics , Alstrom Syndrome/pathology , Bardet-Biedl Syndrome/genetics , Child , Child, Preschool , DNA Mutational Analysis , Ethnicity/genetics , Female , Genetic Association Studies , Heart Defects, Congenital/diagnosis , Heart Defects, Congenital/genetics , Heart Defects, Congenital/pathology , Humans , Hydrocolpos/diagnosis , Hydrocolpos/genetics , Hydrocolpos/pathology , Infant , Male , Middle Aged , Polydactyly/diagnosis , Polydactyly/genetics , Polydactyly/pathology , Uterine Diseases/diagnosis , Uterine Diseases/genetics , Uterine Diseases/pathologyABSTRACT
Liver fibrocystic disease (LFCD), characterized by dilatation of the intrahepatic bile ducts and variable degree of fibrosis, can be present alone or as part of many syndromes, such as Bardet-Biedl syndrome (BBS), Meckel syndrome, Jeune asphyxiating thoracic dysplasia, and Fraser-Jequier-Chen syndrome. We report two cases of LFCD and polydactyly with features similar, but not diagnostic of, BBS. Patient 1 was an 18-month-old boy with mental retardation, polydactyly, chronic renal failure, convergent strabismus, and hepatic fibrosis. Patient 2 was a male neonate with LFCD and polydactyly. Their manifestations could not be diagnosed as any of the previous mentioned entities. Difficulties in the early diagnosis of BBS have been previously reported and this could explain the clinical variability and heterogeneity of manifestations at the time of diagnosis. On the other hand, the existence of liver abnormalities in association with BBS has been previously described, but is rare. Our patients' malformations might represent a new entity where autosomal recessive inheritance is probable, but other patterns cannot be ruled out.
Subject(s)
Liver Cirrhosis/diagnosis , Polydactyly , Bardet-Biedl Syndrome/classification , Caroli Disease/classification , Genes, Recessive , Humans , Infant , Infant, Newborn , Liver/chemistry , Liver/pathology , Liver Cirrhosis/classification , Liver Cirrhosis/genetics , Male , Phenotype , Polydactyly/genetics , SyndromeABSTRACT
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.
