Novel CYCLIN‐O pathogenic variants in a patient presenting with bronchiectasis secondary to reduced generation of multiple motile cilia

Reduced generation of multiple motile cilia (RGMC) represents a rare variant of Primary Ciliary Dyskinesia (PCD), associated with CYCLIN‐O (CCNO) mutations. We report a novel compound mutation in the CCNO gene in an adult Chinese Singaporean exhibiting chronic productive cough since childhood and recurrent sino‐pulmonary infections. Low nasal nitric oxide and bronchiectasis suggests PCD. Bronchoscopy for epithelial and nasal brushings for ciliary studies were repeated after adequate treatment of lower respiratory tract infections. Demonstration of oligo‐cilia via transmission electron microscopy, and detection of CCNO mutation through genetic analysis were utilized to diagnose RGMC. Repeated courses of antibiotics including nebulised antibiotics were used to treat recurrent infections and exacerbations. Airway clearance techniques, immunizations and collaboration with otorhinolaryngologist form part of the long‐term management. Heightened clinical suspicion and adherence to established diagnostic algorithms are essential for timely recognition of this entity. Cilia are microtubule‐based, hair‐like organelles. Structural or functional defects in them impair mucociliary clearance, a hallmark of Primary Ciliary Dyskinesia (PCD). We report a patient with reduced generation of multiple motile cilia (RGMC), a variant of PCD with compound heterozygous variants in the CYCLIN‐O (CCNO) gene (MIM607752; CILD29 MIM615872).