Hereditary interstitial lung diseases manifesting in early childhood in Japan

BACKGROUND: Genetic variations associated with interstitial lung diseases (ILD) have not been extensively studied in Japanese infants. METHODS: Forty-three infants with unexplained lung dysfunction were studied. All 43, 22, and 17 infants underwent analyses of surfactant protein (SP)-C gene (SFTPC) and ATP-binding cassette A3 gene (ABCA3), SP-B gene (SFTPB), and SP-B western blotting, respectively. Two and four underwent assessment of granulocyte macrophage colony-stimulating factor-stimulating phosphorylation of signal transducer and activator of transcription-5 (pSTAT-5) and analyses of FOXF1 gene (FOXF1), respectively. RESULTS: ILD were diagnosed clinically in nine infants: four, three, and two had interstitial pneumonitis, hereditary pulmonary alveolar proteinosis (hPAP), and alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV), respectively. Genetic variations considered responsible were detected in six (67%) of the nine infants with ILD: three with hPAP (SFTPC p.Leu45Arg and p.Gln145fs, and ABCA3 p.Arg1583Trp/p.Val1495CysfsX21), two with interstitial pneumonitis (SFTPC p.Lys63Glu and p.Ser72Asn/p.Gly100Ala), and one with ACD/MPV (FOXF1 p.Leu300ArgfsX79). None showed SFTPB mutations or defects in pSTAT-5. The 17 bron-choalveolar lavage or tracheal aspirates contained enough SP-B protein. CONCLUSION: The SP-C abnormality was most prevalent, and SP-B deficiency was rare in Japanese infants with hereditary-ILD.