SERPINA1 showed the strongest association with FEV1 among smokers (8.41×10−5). It encodes alpha-1 Antitrypsin protein (AAT), mainly produced in the liver and has the primary role of inhibiting neutrophil elastase in the lungs [11]. Protein variants of this gene have been classified based on their migration in an isoelectric pH gradient from A to Z. Among Caucasians, the M allele is the most common allele with six subtypes: M1–M6 with allele frequencies greater than 95 percent and associated with normal AAT levels. The common deficiency variants; S (frequency 0.02–0.03) and Z (frequency 0.01–0.03), are associated with mild and severe reductions in serum AAT levels, respectively [11], [12]. The r 2 between the Z allele rs28929474 and rs3748312 is 0.08 (based on 1000 Genomes Project pilot 1 data from 120 CEU individuals). Our top SNP, rs3748312, is in LD (r 2 = 0.603) with the M1 allele SNP rs6647, but is in very weak LD with M2 rs709932 (r 2 = 0.033) and M3 rs1303 (r 2 = 0.051). The S allele SNP rs45551939 (merged into rs17580) was not found in
