So far, eight genes have been linked to Bardet-Biedl syndrome (BBS), a human disorder characterised by obesity, retinal degeneration, kidney dysfunction and other ailments. MKKS/BBS6, which is also mutated in the developmental disorder McKusick-Kaufman syndrome, is among the least understood of the BBS-linked proteins, but now Michel Leroux and co-authors report that MKKS/BBS6 is a divergent group-II-chaperonin-like protein that is required for cytokinesis (see p. 1007). They show that BBS6 evolved recently from a subunit of CCT, the eukaryotic cytosolic chaperonin. However, unlike chaperonins, BBS6 resides mostly within the pericentriolar material, and its localization is disrupted by disease-linked mutations within its apical domain. The authors provide evidence for a centrosomal role for BBS6 by showing that knocking down BBS6 causes cytokinesis defects. Finally, because BBS6 is enriched in tissues containing ciliated cells, the authors propose that, like other BBS proteins examined, BBS6 may have a basal body/ciliary function that, when lost through mutation, causes Bardet-Biedl syndrome.