The possible mechanism is that Th1 and Th2 cells can produce inflammatory cytokines such as IFN-γ, TNF-α, and IL-4 and mediate cellular and humoral immune responses, and mycoplasma pneumonia can cause abnormal differentiation of T lymphocyte subsets in children with elevated levels of IFN-γ, TNF-α, IL-4, and Th1/Th2 as the main manifestations. The gene discussed is IFNG; the disease is Mycoplasma pneumoniae pneumonia.