Fibroblast growth factor 10 (FGF10) is a signaling molecule with a well-established role for lung branching morphogenesis. Rare heterozygous, deleterious variants in the FGF10 gene are known causes of the lacrimo-auriculo-dento-digital (LADD) syndrome as well as aplasia of lacrimal and salivary glands (ALSG). Previous studies indicate that pathogenic variants in FGF10 can cause lethal human developmental disorders of the lung, but reports on diffuse lung disease caused by pathogenic variants in the FGF10 gene are lacking. We describe four children with postnatal onset of severe diffuse lung disease and heterozygous variants in FGF10, each detected by whole exome or whole genome sequencing. All children presented with postnatal respiratory failure. Two children died within the first 2 days of life, one patient died at age of 12 years and one patient is alive at age of six years, but still symptomatic. One patient presented signs of severe dental caries suggestive for ALSG or LADD-syndrome. Histopathological analysis of lung biopies from the two children with early postpartum demise revealed diffuse developmental disorder representing acinar dysplasia. Sequential biopsies of the child with survival until the age of 12 years revealed alveolar simplification and progressive interstitial fibrosis. Our report extends the phenotype of FGF10-related disorders to diffuse developmental disorders of the lung and early onset lung fibrosis. Therefore, FGF10-related disorder should be considered even without previously described syndromic stigmata in children with postnatal respiratory distress, not only when leading to death in the neonatal period but also in case of persistent respiratory complaints.

Background: Newborn screening (NBS) has been shown to improve CF disease course and has been widely implemented worldwide. This monocentric study compared children diagnosed by NBS vs. a cohort preceding the implementation of NBS in Germany in 2016 to evaluate ascribed benefits of NBS. Methods: We compared all children with confirmed CF diagnosis (n=19, “NBS group”) out of all children presenting with positive NBS at our center after implementation of NBS (n=100) to children diagnosed with CF at our center within 4 years before NBS implementation (n=29, “pre-NBS group”) for outcomes of anthropometry, gastrointestinal and pulmonary disease manifestations and respiratory microbiology. Results: Children diagnosed by NBS had a lower incidence of initial feeding problems (15% vs. 41%), had a higher BMI z-score at diagnosis and higher mean z-scores for BMI, weight and length during the study period. Children in the pre-NBS group displayed higher proportions of oxygen-dependent pulmonary exacerbations (10% vs. 0%), a significantly lower amount of normal bacterial flora (p=0.005) along with a significantly higher number of throat swab cultures positive for Pseudomonas aeruginosa (p=0.0154) in the first year of life. Yet, pulmonary imaging did not reveal less pulmonary morbidity in the NBS compared to the pre-NBS group. Conclusions: Our results confirm that NBS for CF leads to earlier diagnosis and improves nutritional outcomes in early childhood. Although trajectories of structural lung damage at early age were unaffected by NBS, NBS positive CF patients at preschool age displayed less severe pulmonary exacerbations and pathological bacteria in throat swabs.