PCD Diagnosis by Super resolution (3DSIM) microscopy

Primary ciliary dyskinesia (PCD) is a heterogeneous recessive genetic disease characterized by impaired mucociliary clearance. PCD is currently diagnosed by analysis of transmission electron microscopy micrographs or genome sequencing of biallelic pathogenic variants in one of 37 known PCD genes. Despite recent advances in the genetics of PCD, there are suspected PCD cases that remain unresolved. Methods: We used immunofluorescence microscopy together with 3DSIM super-resolution microscopy (SRM) on airway epithelial cells freshly isolated from nostril of patients or airway cells grown on air liquid interphase to confirm or refute cases of PCD where transmission electron microscopy was non-diagnostic or where variants of unknown significance were identified in known PCD genes by genetic testing. In all cases, the laboratory technician developing and analyzing the images was blind to the TEM and genetic results of the patient. Results: To date, 7 patients with possible or confirmed PCD have been recruited and imaged by super-resolution microscopy. In all cases, SRM was helpful in either confirming or refuting the diagnosis of PCD. This includes cases with DNAH11, CCDC39, CCDC40, DNAH5, RPGR and CCNO variants. Conclusions: SRM can be a useful diagnostic tool to either confirm or refute the diagnosis of PCD in cases that cannot be solved with either transmission electron microscopy or current clinical genetic testing.