Bardet–Biedl syndrome (BBS) was classified as a ciliopathy in 2003, and eight of the highly conserved BBS proteins (BBS1, BBS2, BBS4, BBS5, BBS7, BBS8, BBS9, and BBIP10) establish a stable protein complex called the BBSome that undergoes IFT. The gene discussed is BBS4; the disease is Bardet-Biedl syndrome.