Clinical observations also confirm the pathogenetic role of NETs in CF, by revealing a positive correlation between the impairment of respiratory function and the level of free DNA or elastase in CF airways, or the level of MPO and antibodies to PAD4 in circulating blood (Marcos et al., 2015; Dittrich et al., 2018; Yadav et al., 2019). This evidence concerns the gene MPO and cystic fibrosis.