Severe Bronchiectasis and Chronic Rhinosinusitis Due to Homozygous WFDC2 Variants: The First Three Cases Reported from Japan

We report the first three cases of bronchiectasis caused by homozygous WFDC2 variants in Japan. The ages at diagnosis of bronchiectasis were 18, 24, and 16 years, and all patients had a history of chronic sinusitis since childhood. Despite low nasal nitric oxide levels, the radiologic features resembled those of cystic fibrosis, characterized by bronchiectasis predominantly in the upper lobes. All patients experienced frequent exacerbations and respiratory dysfunction, even with long-term macrolide therapy. Consequently, two of the three patients required lung transplantation. Considering the possibility of founder mutations, WFDC2 variants should be included in diagnostic panels for patients with sinopulmonary disease in Asian populations.