Six polymorphic sites within the NOS3 gene (924A/G, 788C/T, 691C/T, 774C/T, 894G/T, and 1998C/G) in 345 AATD patients (PI*Z homozygotes or compound heterozygotes of PI*Z with other deficiency alleles) and 93 control individuals were analysed. The gene discussed is NOS3; the disease is alpha 1-antitrypsin deficiency.