RATIONALE: The relationship between clinical phenotype of childhood primary 
ciliary dyskinesia (PCD) and ultrastructural defects and genotype is poorly 
defined.
OBJECTIVES: To delineate clinical features of childhood PCD and their 
associations with ultrastructural defects and genotype.
METHODS: A total of 118 participants younger than 19 years old with PCD were 
evaluated prospectively at six centers in North America using standardized 
procedures for diagnostic testing, spirometry, chest computed tomography, 
respiratory cultures, and clinical phenotyping.
MEASUREMENTS AND MAIN RESULTS: Clinical features included neonatal respiratory 
distress (82%), chronic cough (99%), and chronic nasal congestion (97%). There 
were no differences in clinical features or respiratory pathogens in subjects 
with outer dynein arm (ODA) defects (ODA alone; n = 54) and ODA plus inner 
dynein arm (IDA) defects (ODA + IDA; n = 18) versus subjects with IDA and 
central apparatus defects with microtubular disorganization (IDA/CA/MTD; 
n = 40). Median FEV1 was worse in the IDA/CA/MTD group (72% predicted) versus 
the combined ODA groups (92% predicted; P = 0.003). Median body mass index was 
lower in the IDA/CA/MTD group (46th percentile) versus the ODA groups (70th 
percentile; P = 0.003). For all 118 subjects, median number of lobes with 
bronchiectasis was three and alveolar consolidation was two. However, the 5- to 
11-year-old IDA/CA/MTD group had more lobes of bronchiectasis (median, 5; 
P = 0.0008) and consolidation (median, 3; P = 0.0001) compared with the ODA 
groups (median, 3 and 2, respectively). Similar findings were observed when 
limited to participants with biallelic mutations.
CONCLUSIONS: Lung disease was heterogeneous across all ultrastructural and 
genotype groups, but worse in those with IDA/CA/MTD ultrastructural defects, 
most of whom had biallelic mutations in CCDC39 or CCDC40.