Genotype-Phenotype Correlation in a Group of Italian Patients With Primary Ciliary Dyskinesia

Introduction: Primary Ciliary Dyskinesia (PCD) is a rare genetic disorder characterized by abnormalities in the motile cilia. Diagnosis could be hard to make, but genetic analysis could be important for the diagnosis and for defining prognosis. Aim of the Study: To evaluate the clinical, ultrastructural, and molecular characteristics of a cohort of PCD subjects. Materials and Methods: The study cohort included PCD patients enrolled in two Italian centers. Clinical data were retrospectively collected consulting medical records. All patients underwent nasal brushing and peripheral blood sampling for ultrastructural analysis of motile cilia and genetic testing, respectively. Results: A total of 39 patients with PCD were enrolled (median age 25.5 years, range 2.5–54.3 years). All patients showed common clinical features, which included SIT in 22/39 (56.4%), chronic rhinitis in 31/39 (79.5%), chronic sinusitis in 26/37 (66.7%), chronic cough in 32/39 (82.1%), and neonatal respiratory distress in 46.2% (18/39). The genetic defect was identified in 27/39 patients (69.2%), while a diagnostic ultrastructure was found in 27/35 (77.1%). Assessing genotype-phenotype correlations, subjects with biallelic pathogenic variants in CCDC39 and CCDC40 genes had a significantly lower forced expiratory volume in the first second of exhalation value (p = 0.017) than subjects with pathogenic variants in DNAH5 or in other PCD-related genes. Conclusions: Our study further highlights the high heterogeneity of ultrastructural defects and genetics characterizing patients with PCD, as well as providing additional evidence that patients with biallelic pathogenic variants in CCDC39 or CCDC40 display a worse clinical phenotype than patients with pathogenic variants in other PCD genes.