α1-Antitrypsin deficiency (AATD)
B. Assess serum α1-antitrypsin level and genotype
The key to the correct diagnosis in this case is the severe obstructive pattern on pulmonary function testing, CT of the chest demonstrating lower lobe predominant emphysema and bronchiectasis, and presentation during the fourth decade of life.
Bronchoscopy with bronchoalveolar lavage and transbronchial biopsy may be reasonable in pursuit of an infectious or ciliary dyskinesia etiology related to this patient’s bronchiectasis but is unlikely to provide a unifying diagnosis with her emphysema. Inhaled nasal nitric oxide and ciliary dyskinesia genetic testing can be used to evaluate for ciliary dyskinesia, but the absence of neonatal respiratory distress, year-round daily cough and nasal congestion beginning before age 6 months, and situs inversus makes this diagnosis unlikely. A diagnosis of cystic fibrosis is also unlikely, given the distribution and severity of this patient’s bronchiectasis and emphysema (predominantly upper lobes in cystic fibrosis vs lower lobes in AATD) without extrapulmonary manifestations or family history.