C61-03 Uncovering Primary Ciliary Dyskinesia in Colombia: Insights From a National Referral Program Based in Medellin

Background Primary Ciliary Dyskinesia (PCD) is a rare, genetically heterogeneous ciliopathy with an autosomal recessive inheritance pattern. Diagnosis remains challenging, especially in Latin America due to limited access to specialized tools. In Colombia, the phenotypic and genotypic spectrum of PCD is poorly characterized. This study describes clinical features, genetic mutations, diagnostic approaches, and treatments in patients evaluated through a national referral program based in Medellín. Objectives To characterize clinical, genetic, and diagnostic features of Primary Ciliary Dyskinesia in Colombian patients Methods We conducted a retrospective, descriptive study of patients with suspected or genetically confirmed PCD. Data were extracted from medical records, including demographics, clinical presentation, genetic testing, electron microscopy, pulmonary function, and microbiology. Diagnostic modalities varied across patients due to resource limitations. Results Thirty-seven patients were included. The median age at diagnosis was 16 years (IQR: 7-32), significantly older than reported in other international cohorts. The median PICADAR score was 4 (IQR: 3-6). All patients presented with persistent wet cough prior to diagnosis. Other common features included chronic rhinitis (83.3%), respiratory distress syndrome (RDS) at birth (43%), pneumonia (78.4%), recurrent sinusitis or wheezing (70.3%), and bronchiectasis (63.3%). Situs anomalies were present in 18.9%, and congenital heart disease in 5.4%. Asthma was diagnosed in 48% of patients. Electron microscopy was performed in 11 patients, with compatible findings for PCD in 13.5%. Genetic testing confirmed biallelic mutations in 27 patients. The most frequently identified mutation was in the HYDIN gene (8/27, 29.6%), followed by RSPH1 (4/27, 14.8%), DNAJB13 (4/27, 14.8%), ZMYND10 (2/27, 7.4%), TTC25 (2/27, 7.4%), CCNO (2/27, 7.4%), ARMC4 (1/27, 3.7%), CCDC39 (1/27, 3.7%), DNAH5 (1/27, 3.7%), DNAH11 (1/27, 3.7%), and ODAD4 (1/27, 3.7%). Bronchiectasis was observed in 63.3% of patients. Pulmonary function testing showed obstructive patterns in 21.6% of cases, with bronchodilator responsiveness in only 13.5%. Pseudomonas aeruginosa was the most commonly isolated pathogen in sputum cultures (29.3%). Most patients (94.6%) received outpatient respiratory therapy, typically including bronchodilators and hypertonic saline. Conclusion PCD diagnosis in Colombia faces significant challenges, including delayed recognition influenced by multiple factors: a low prevalence of laterality defects, frequent HYDIN mutation, often excluded from standard PCD genetic panels, and limited access to key diagnostic tools such as immunofluorescence, nasal nitric oxide measurement, and high-speed video microscopy. These limitations complicate timely and accurate diagnosis. Expanding access to comprehensive diagnostic resources and promoting early identification are essential to improve clinical outcomes for patients with PCD.