Molecular basis of the obesity associated with Bardet–Biedl syndrome

Bardet–Biedl Syndrome (BBS) is a rare human hereditary disorder associated with several features including obesity, retinopathy, renal defects, polydactyly, learning disabilities and hypogenitalism. This article discusses the abnormalities accounting for energy imbalance leading to obesity in BBS, with emphasis on the recent evidence pointing to aberrations in hypothalamic action of leptin. Indeed, BBS proteins have emerged as important mediators of leptin receptor trafficking, and loss of BBS genes results in leptin resistance that could be due to abnormal leptin receptor handling in a subset of leptin-responsive neurons. These recent discoveries hold promise for improved clinical management of BBS patients. The relevance of these findings to non-syndromic common obesity is also discussed.