MCC-specific inactivation of miR-34/miR-449 using a FOXJ1-Cre driver phenocopies the ED deficits of the germline miR-34b/c−/−/miR-449−/− male mice, reinforcing the view that loss of multicilia in the EDs is the primary cause of their male infertility. The gene discussed is FOXJ1; the disease is male infertility.