Supplementary Material for: SHH variant in a father and a son with tracheobronchial malformation

Introduction
Congenital tracheobronchial stenosis (CTBS) is a rare disease of in most cases unknown etiology. In a previous cohort of patients with CTBS, a mosaic variant in the SHH-gene was identified.
Case presentation
We hereby report a son (case 1) and his father (case 2) with tracheobronchial malformation. In the severely affected proband a rare SHH variant (c.376G>A p.(Glu126Lys)) was found, which appeared to be inherited from his father who had a similar clinical phenotype. This variant was found to be de novo in the father.
Conclusion
We identified a variant in SHH as a possible cause of familial tracheobronchial malformation. This case underscores a possible association between the SHH gene and trachea development. Notably, this variant can present with severe symptoms in infancy, but signs and symptoms may be more attenuated in adulthood.