Bardet-Biedl syndrome Bardet-Biedl syndrome 5 BBS5 is a ciliopathy associated with severe and early-onset retinal dystrophy, postaxial polydactyly, obesity, renal dysfunction, hypogonadism, and learning difficulties (summary by Scheidecker et al., 2015). Patients described by Young et al. (1999) and Moore et al. (2005) with mutations in the BBS5 gene did not have polydactyly. The contribution of BBS5 mutations to all cases of BBS has been estimated at 2% (Li et al., 2004) and 0.40% (Zaghloul and Katsanis, 2009). Hannah McLaren OMIM:615983 Orphanet:118987