Also under the additive model, IL-9 rs2069879 polymorphism was significantly associated with HT (before adjustment: P<0.001, OR=0.05, 95%CI=0.03-0.09; adjusted for sex and age: P<0.001, OR=0.05, 95%CI=0.03-0.10) (Table 4). This evidence concerns the gene IL9 and hematocrit.