Thus, a BBS-associated gene interacts with NPHP complex genes in C. elegans, but not in mouse, whereas a BBS-associated gene interacts with an MKS complex gene in mouse, but not in C. elegans. BBSome and transition zone complex genes interact in both organisms, but the specific genetic interactions differ between nematodes and mammals, suggesting that some ciliopathy gene interactions are species and/or cell-type specific, and may reflect evolutionary differences in the function of the nematode and mammalian MKS and NPHP complexes. Here, MKS1 is linked to ciliopathy.