Primary ciliary dyskinesia

Abstract

Primary ciliary dyskinesia (PCD) is a rare heterogeneous genetic disorder affecting ciliary function. Genes coding for various ciliary structural proteins or cytoplasmic proteins responsible for the assembly of cilia can be mutated resulting in abnormal ciliary function. However, despite the diversity of genotypes that can cause PCD the clinical phenotypes of PCD are all remarkably similar. The main clinical symptoms are caused by a lack of mucociliary clearance. Worryingly many patients are diagnosed late despite their classical, lifelong symptoms of a daily wet sounding cough and rhinosinusitis. Even when PCD is suspected, poor access to specialist diagnostic centres may delay diagnosis. Currently, diagnostic testing includes screening of nasal nitric oxide, followed by nasal brushing to obtain ciliated epithelial strips for high-speed video analysis of ciliary function. This is typically followed by transmission electron microscopy and in difficult cases by ciliated cell culture. Emerging tests including immunofluorescence and genetic examination are the focus of intense research and are likely to feature more in the future. Despite a greater understanding of the pathogenesis of PCD and improved diagnostic testing, management strategies are currently based on expert opinion with little, if any, evidence base.