Finally, we examined the expression of several known genes found to be associated with COPD based on GWAS studies [23], including HHIP (Hedgehog Interacting Protein), FAM13A (Family With Sequence Similarity 13 Member A), ROBO2 (Roundabout Guidance Receptor 2), and ANKRD18A (Ankyrin Repeat Domain 18A). This evidence concerns the gene HHIP and chronic obstructive pulmonary disease.