This cross-sectional and longitudinal observational study is to gather data on the utility of tests that are used to make a diagnosis of primary ciliary dyskinesia (PCD). There is new testing available, called nasal nitric oxide testing, that non-invasively measures nitric oxide levels in the sinus cavity. Individuals with PCD characteristically have low levels, but this testing does not have extensive data from everyday clinical practice. The objective of this proposal is to improve the diagnostic approach to children and adults with clinical concerns for primary ciliary dyskinesia (PCD).