RESUMEN
Bardet-Biedl syndrome (BBS) is an autosomal recessive disease characterized by retinal dystrophy, obesity, postaxial polydactyly, learning disabilities, renal involvement, and male hypogenitalism. BBS is genetically heterogeneous, and to date 18 genes (BBS1-18) have been described. Mutations in known BBS genes account for approximately 70-80% of cases, and triallelic inheritance has been suggested in about 5%. Many minor features can be helpful in making the clinical diagnosis. Recently, the use of next-generation sequencing technologies has accelerated the identification of novel genes and causative disease mutations in known genes. This report presents a concise overview of the current knowledge on clinical data in BBS and the progress in molecular genetics research. A future objective will be the development of BBS diagnosis kits in order to offer genetic counseling for families at risk.
RESUMEN
Bardet-Biedl syndrome (BBS, OMIM 209900) is a rare genetic disorder characterized by obesity, retinitis pigmentosa, post axial polydactyly, cognitive impairment, renal anomalies and hypogonadism. The aim of this study is to provide a comprehensive clinical and molecular analysis of a cohort of 11 Tunisian BBS consanguineous families in order to give insight into clinical and genetic spectrum and the genotype-phenotype correlations. Molecular analysis using combined sequence capture and high-throughput sequencing of 30 ciliopathies genes revealed 11 mutations in 11 studied families. Five mutations were novel and six were previously described. Novel mutations included c.1110G>A and c.39delA (p.G13fs*41) in BBS1, c.115+5G>A in BBS2, c.1272+1G>A in BBS6, c.1181_1182insGCATTTATACC in BBS10 (p.S396Lfs*6). Described mutations included c.436C>T (p.R146*) and c.1473+4A>G in BBS1, c.565C> (p.R189*) in BBS2, deletion of exons 4-6 in BBS4, c.149T>G (p.L50R) in BBS5, and c.459+1G>A in BBS8; most frequent mutations were described in BBS1 (4/11, 37%) and BBS2 (2/11, 18%) genes. No phenotype-genotype correlation was evidenced. This data expands the mutations profile of BBS genes in Tunisia and suggests a divergence of the genetic spectrum comparing Tunisian and other populations.