To examine whether MKS1 and the MKS complex have roles in ciliary trafficking that may parallel those of other ciliopathy complexes, we tested whether Mks1 interacts genetically with the BBSome component Bbs4. We generated Mks1; Bbs4 double mutant embryos, using the previously described ENU-induced Mks1krc allele [39] and a Bbs4 genetrap allele (here referred to as Bbs4-/-) [38]. The gene discussed is BBS4; the disease is ciliopathy.