Primary ciliary dyskinesia and upper airway diseases.

Primary ciliary dyskinesia (PCD) is a rare and difficult-to-diagnose disease with morbidity related to infections of the upper and lower respiratory tract. The disease is caused by mutations in genes that are required for proper ciliary function. The defect in ciliary function results in reduced or absent mucociliary clearance, thereby predisposing the affected individual to repeated bacterial infections. Recent advances in the understanding of the basic biology and function of the cilium have led to the identification of some of the genes that are mutated in cases of PCD. Further studies of this disease will likely lead to earlier diagnosis, better treatment, and improved outcomes.