Table 1

Diagnostic testing in primary cell dyskinesia (PCD)

Test	Interpretation	Role in PCD diagnosis
Saccharin test3	False negatives and false positives, screening test at best	Not useful to diagnose or exclude PCD
Radionuclide mucociliary clearance4	Good sensitivity and specificity but only limited experience or access in most centres	Not useful to diagnose or exclude PCD
Nasal nitric oxide5	Used as the screening test of choice, also low in cystic fibrosis and other conditions; now also part of the diagnostic investigation	Normal nasal nitric oxide = PCD very unlikely
Ciliary motility studies	Can be affected by recent viral infection	Normal ciliary beat frequency and pattern = PCD excluded If abnormal, repeat after treatment of infection or proceed to ciliary culture Abnormal ciliary beat frequency and/or pattern on an adequate sample = definite PCD
Transmission electron microscopy	Can be affected by recent viral infection	Presence of known disease producing structural abnormality = definite PCD Can be normal with definite PCD
Culture of ciliary biopsy6	Cilia regrown in culture, used to differentiate secondary ciliary dyskinesia in PCD	Normal ciliary beat frequency and pattern = PCD excluded Abnormal ciliary beat frequency and/or pattern on an adequate sample = definite PCD
Genetic studies	>250 potential loci, very few known genes	Two known disease producing mutations in trans = definite PCD Can be no known mutations detected with definite PCD
Immunofluorescence of ciliary proteins7	Limited experience only and applicable to date to very few proteins	Insufficient evidence to evaluate a role in clinical practice Not a stand-alone diagnostic test