Bardet-Biedl syndrome

Bardet-Biedl syndrome (BBS) is a rare, genetically heterogeneous ciliopathy — a disorder caused by dysfunction of cilia, the tiny hair-like structures found on nearly every cell in the body that play critical roles in cellular signaling and development. BBS is characterized by a combination of primary features including progressive rod-cone dystrophy (retinal degeneration leading to vision loss, often beginning in childhood), truncal obesity that typically manifests in early childhood, polydactyly (extra fingers or toes, usually postaxial), renal anomalies (structural and/or functional kidney disease, which is a major cause of morbidity and mortality), learning difficulties or intellectual disability of variable severity, and hypogonadism affecting the reproductive system. The syndrome was historically known as Laurence-Moon-Bardet-Biedl syndrome, though Laurence-Moon syndrome is now generally considered a distinct entity. BBS affects multiple organ systems beyond the cardinal features. Patients may experience speech and language delays, behavioral difficulties, diabetes mellitus, cardiovascular abnormalities, hepatic fibrosis, anosmia (reduced sense of smell), and dental anomalies. Renal disease, ranging from structural malformations to chronic kidney disease, is a leading cause of serious complications. The retinal dystrophy is progressive, with most patients becoming legally blind by the second or third decade of life. At least 26 genes (BBS1 through BBS26) have been identified as causative, with BBS1 and BBS10 being the most commonly mutated in European populations. The proteins encoded by these genes are involved in the formation and function of the primary cilium and the BBSome complex. Currently, there is no cure for Bardet-Biedl syndrome, and management is primarily supportive and multidisciplinary. Treatment involves regular ophthalmologic monitoring, renal function surveillance, management of obesity through dietary and behavioral interventions, educational support, and hormonal therapy for hypogonadism when indicated. In 2022, setmelanotide (Imcivree), a melanocortin-4 receptor agonist, was approved in several jurisdictions for the treatment of obesity associated with BBS in patients aged 6 years and older, representing the first targeted pharmacological therapy for a feature of this condition. Early diagnosis and coordinated care involving geneticists, nephrologists, ophthalmologists, endocrinologists, and other specialists are essential to optimize outcomes.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

Common questions about Bardet-Biedl syndrome