Childhood interstitial and diffuse lung disease (ChILD) is a compilation of rare pediatric diseases affecting lung parenchyma and airways, varying in severity and outcome. A subgroup of ChILD includes diseases of surfactant dysfunction, which typically present in the newborn period as neonatal respiratory distress syndrome and are associated with congenital alveolar proteinosis. Genetic causes of errors in surfactant metabolism include mutations in surfactant protein (SP)-B, SP-C, and an ATP-binding cassette protein (ABCA3). Thyroid transcription factor (TTF)-1 mutations, too, have been implicated in cases of surfactant dysfunction, although classically in the form of brain-thyroid-lung disease, in which the affected patient also has neurologic impairment and thyroid dysfunction. However, in this issue of CHEST (see page 794), Hamvas et al1 specifically describe the pulmonary phenotype associated with TTF-1 mutations, which may or may not include neurologic or thyroid abnormalities.