CFTR and inborn error of immunity: Sweat chloride test and CFTR analysis; nasal nitric oxide plus transmission electron microscopy and beat analysis of ciliary ultrastructure and motility, respectively, on nasal brushing; and immune status assessment (including serum total immunoglobulins levels and response to immunizations) for ruling out cystic fibrosis (CF), primary ciliary dyskinesia (PCD) and primary immunodeficiency (PID), respectively, were negative or normal.