The COPD associated region on chromosome 15 spans seven genes (Figure 2). Cholinergic nicotinic receptor subtypes α3, α5 and β4; IREB2, PSMA4, NP_001013641.2 (a gene with unknown function) and Q9UD29 (Surfactant protein B (SP-B)-binding protein). A partial map of the region is shown in online Figure S2. SP-B binding protein is a DNA binding protein which binds to the promoter of SP-B and affects its expression [10]. Since SP-B is a critical surfactant in the lungs [11], we sequenced the SP-B binding protein in 30 COPD subjects who are homozygous for the risk allele of rs8034191 but did not identify any polymorphisms in this gene.
