Furthermore, a number of other UPS proteins have been implicated in ciliopathies including TOPORS, an E3 ligase located at the basal body and cilium that is mutated in retinitis pigmentosa (RP) (Chakarova et al., 2007), and TRIM32, an E3 mutated in Bardet-Biedl syndrome (BBS) (Chiang et al., 2006). Here, HMBS is linked to retinitis pigmentosa.