= 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 HapMap (version24). It is possible that the signal observed in our data is due to variants with effects on gene expression and/or protein levels, and this idea is supported by a previous study showing novel variants in SERPINA1 to be associated with increased susceptibility to COPD independently of the Z allele [13]. The relatively strong signal observed in our study suggests a possible role for variants in SERPINA1 in smokers at the general population level beyond that observed in carriers of known deficient alleles.
