(2) The FHS cohort was recruited over three decades, while our cohorts represent more recent recruitments (in the last 5–10 years)-smoking habits have changed over time, and it is also possible that COPD clinical characteristics have changed over this period; (3) Our cohorts include a greater proportion of severe COPD subjects than in FHS; and (4) There could be differences in linkage disequilibrium patterns between study populations. Further studies will be required to define the specific genetic determinants influencing COPD on chromosome 15, the relationship of these genetic factors to smoking behavior, and the characteristics of COPD subjects influenced by these genetic determinants.
