Spectrum of Diagnoses
The 683 subjects were classified by site investigators in the following categories: lung developmental dysplasia; alveolar growth disorder; surfactant dysfunction; pulmonary alveolar proteinosis due to other causes; pulmonary interstitial glycogenosis; neuroendocrine cell hyperplasia of infancy (NEHI); bronchiolitis obliterans; alveolar hemorrhage; chILD associated with connective tissue or immune-mediated disorders; other specific or multisystem disorders; environmental / toxic / drug related chILD; or unclassified ILD (Table 2 ). To date, the most frequent diagnosis is NEHI, with a total of 155 subjects comprising 22.7% of all registry enrollment. The second most frequent diagnosis is ILD associated with connective tissue or immune-mediated disorders (113 subjects, 16.5%). For 11% of enrolled subjects, the diagnostic designation was ‘unclassified ILD’ (Figure 2 ).
Within these broader categories, subclassifications or specific diagnoses could be subsequently selected by site investigators. For example, within the surfactant metabolic dysfunction category, surfactant protein-C gene (SFPTC ) is most frequently reported (37 subjects; 45.1% of surfactant metabolic dysfunction category), while ILD due to ABCA3 disruption is reported in 30 (36.6%) of subjects. The most frequently enrolled subtype of bronchiolitis obliterans is post-infectious (34 subjects, 45.3% of bronchiolitis obliterans category).