ABSTRACT: Meckel Syndrome, Nephronophthisis, Joubert Syndrome, and Bardet-Biedl Syndrome have mutations in proteins that localize to the ciliary transition zone (TZ). The phenotypically distinct syndromes suggest these TZ proteins have differing functions. However, mutations in a single TZ gene can result in multiple syndromes suggesting the phenotype is influenced by modifier genes. We performed a comprehensive analysis of ten zebrafish TZ mutants including mks1, tmem216, tmem67, rpgrip1l, cc2d2a, b9d2, cep290, tctn1, nphp1, and nphp4, as well as mutants in ift88 and ift172. Our data indicate variations in phenotypes exists between different TZ mutants, supporting different tissue specific functions of these TZ genes. Further we observed phenotypic variations within progeny of a single TZ mutant, reminiscent of multiple disease syndromes being associated with mutations in one gene. In some mutants the dynamics of the phenotype became complex with transitory phenotypes that are corrected over time. We have also demonstrated that multiple-guide derived CRISPR/Cas9 F0 “Crispant” embryos recapitulate zygotic null phenotypes, and rapidly identified ciliary phenotypes in 11 cilia-associated gene candidates (ankfn1, ccdc65, cfap57, fhad1, nme7, pacrg, saxo2, c1orf194, ttc26, zmynd12, and cfap52).
