BBS1 and Bardet-Biedl syndrome: It is, together with BBS1, the major contributor to BBS accounting for 20% of all cases (Stoetzel et al., 2006; Forsythe and Beales, 2013), with remarkable exceptions in ethnically homogeneous groups such as Danish (43%; Hjortshøj et al., 2010) or Spanish BBS cohorts (8.3%; Álvarez-Satta et al., 2014).