Fourteen genes are known to be associated with BBS: BBS1 (mutated in 40% of BSS families), BBS2 (mutated in 20% of BSS families), ARL6/BBS3, BBS4 (mutated in 3-6% of BSS families), BBS5 (mutated in 2% of BSS families), MKKS/BBS6, BBS7, TTC8/BBS8, B1/BBS9, BBS10, TRIM32/BBS11, BBS12, MKS1/BBS13, and CEP290/BBS14 (from http://www.sph.uth.tmc.edu/retnet/). Here, TTC8 is linked to Bardet-Biedl syndrome.