Diagnostic Role of Immunofluorescence Analysis in Primary Ciliary Dyskinesia-Suspected Individuals

<b>Background/Objectives</b>: Primary ciliary dyskinesia (PCD) (OMIM: 244400) is a hereditary, rare disorder with a high prevalence in Turkey due to a high rate of consanguinity. The disorder is caused by malfunctioning motile cilia and is characterized by a variety of clinical symptoms including sinusitis, otitis media and chronic obstructive pulmonary disease. This study presents the first assessment of the efficacy of immunofluorescence (IF) labeling for diagnosing PCD in Turkey by correlating IF with clinical observations when genetic data are scarce. <b>Methods</b>: We have a cohort of 54 PCD-suspected individuals with an age range of 5-27 years classified into two groups: group A with available genomic data (8 individuals) and group B with no available genomic data (46 individuals). We performed immunofluorescence analysis to confirm the pathogenicity of the variants in individuals with a prior genetic diagnosis and to confirm a PCD diagnosis in individuals with typical PCD symptoms and no genetic diagnosis. <b>Results</b>: All individuals had airway infections and displayed clinical symptoms of PCD. Our data revealed an absence of outer dynein arm dynein heavy chain DNAH5 in individuals with pathogenic variants in <i>DNAH5</i> and <i>DNAAF1</i> and in 17 other PCD-suspected individuals, an absence of nexin-dynein regulatory complex component GAS8 in 8 PCD-suspected individuals, an absence of outer dynein arm dynein heavy chain DNAH11 in 6 PCD-suspected individuals and an absence of radial spoke head component RSPH9 in 2 PCD-suspected individuals. Furthermore, the pathogenicity of <i>ARMC4</i> variants was confirmed by the absence of the outer dynein arm docking complex component ARMC4 and the proximal localization of DNAH5. <b>Conclusions</b>: Immunofluorescence analysis, owing to its lower cost and quicker turnaround time, proves to be a powerful tool for diagnosing PCD even in the absence of genetic data or electron microscopy results.