IL9 and skin disorder: Moreover, the development of specific dermatitis could be analyzed by monitoring the changes of IL-9 and PU.1 gene levels (Ma et al., 2014; Schlapbach et al., 2014; Ciccia et al., 2016), suggesting that Th9 cells not only participate in the development of allergic diseases, but may also be a new target for clinical monitoring of related clinical diseases.