Deficiency in the serine protease inhibitor, alpha-1 antitrypsin (AAT), is known to cause emphysema and liver disease. Other manifestations, including airway disease or skin disorders, have also been described. A 44-year-old woman presented to our emergency department with dyspnea and respiratory insufficiency. She had never smoked, and had been diagnosed with COPD 9 years earlier. Three months previously, she had suffered a pulmonary embolism. Chest computed tomography scan revealed severe cystic bronchiectasis with destruction of the lung parenchyma. The sweat test was normal and there was no evidence of the cystic fibrosis transmembrane conductance regulator (CFTR) mutation. Capillary zone electrophoresis showed a decrease of alpha-1 globin band and AAT levels were below the quantification limit (<25 mg/dL). No S or Z mutation was identified, but sequencing analysis found a homozygous cytosine and adenine (CA) insertion in exon 2 of the SERPINA-1 gene, probably leading to a dysfunctional protein (PI Null/Null). This mutation has not been previously identified. The atypical presentation of the patient, with severe cystic bronchiectasis, highlights AAT deficiency as a differential diagnosis in bronchiectasis. Further, awareness should be raised regarding a possible increased risk of thromboembolism associated with AAT deficiency.