Among ever-smokers, rs3748312 in serpin peptidase inhibitor, clade A, member 1 (SERPINA1) on chromosome 14, also known as alpha-1 antitrypsin (AAT) showed the strongest association with FEV1. SNP rs298028 in Phosphodiesterase 4D, cAMP-specific (phosphodiesterase E3 dunce homolog, Drosophila) (PDE4D) on chromosome 5 showed the second strongest association with FEV1, followed by MACROD2.
