It is important to note that there is accumulating evidence that genetic polymorphism in genes encoding components of the PLAU-PLAUR regulatory network constitute risk factors for the development of COPD e.g. polymorphisms spanning Serpin peptidase inhibitor, clade E (SERPINE2) have shown significant association with COPD susceptibility, FEV1 and FEV1/FVC [31]. Here, SERPINE2 is linked to chronic obstructive pulmonary disease.