The subgroup analysis revealed that mutations in LRP1B were more frequently observed in COPD patients among non-smokers (21.7% in COPD Vs 8.2% in non-COPD, p = 0.06) and smokers (40% in COPD Vs 23.7% in non-COPD, p = 0.14) although the differences were not statistically significant largely due to the limited sample size in subgroup (Supplementary Fig. S1). This evidence concerns the gene LRP1B and chronic obstructive pulmonary disease.