Interstitial lung diseases (ILD) in children represent a heterogeneous group of rare and not well defined disorders. Genetic abnormalities of surfactant proteins B (SFTPB) and more recently C (SFTPC) have been shown to be related to these pathologies. However, variability in the lung disease phenotype suggests the involvement of other surfactant-associated genes such as ABCA3 (ATP-binding cassette, sub-family A, member, 3). Thus, the aim of this project is: 1) to assess the prevalence of SFTPC mutation in children with chronic lung diseases, 2) to precise clinical and radiological features of children with SFTPC mutation, and 3) to identify environmental or genetic factors that may explain the extreme variability of this disease.