The generation of multiciliated cells (MCCs) is required for the proper function of many tissues, including the respiratory tract, brain, and germline. Defects in MCC development have been demonstrated to cause a subclass of mucociliary clearance disorders termed reduced generation of multiple motile cilia (RGMC). To date, only two genes, Multicilin (MCIDAS) and cyclin O (CCNO) have been identified in this disorder in humans.

We thank the Ministerio de Economía y Competitividad (MINECO) for funding to TS (BFU2012-39521) and MAV (SAF2012-38140; Fondo de Investigación Sanitaria (RD12/0042/0014); FEDER Funds); G.G.-G. is supported by ISCIII (PI13/00864); V.C. is funded by the Associazione Italiana per Ricerca sul Cancro (AIRC), the European Research Council (ERC) consolidator grant (614541), the Association for International Cancer Research (AICR) (13-0026), the Giovanni Armenise Award to V.C., the Epigen Progetto Bandiera (4.7) and the Fondazione Telethon (GGP13071); G.P. was supported by AIRC Borsa: Fondazione Giovanna Ciani Rif. 16444; S.S.B. was supported by a fellowship from Fundació La Caixa; P.A.K. was supported by an Early Postdoc Mobility Fellowship from the Swiss National Science Foundation; and B.T. was supported by a Severo Ochoa FPI Fellowship (MINECO). IRB Barcelona is a Severo Ochoa Award of Excellence Recipient (MINECO).