These abnormalities likely all impact fertility, leading to the infertility or subfertility observed in the patients with endometriosis 61, just like the toxic effects of those increased concentrations of Th1 cytokines such as TNF-α, IL-1β, IL-4, IL-6, IL-12, and IFN-γ in women with endometriosis 132-139. The gene discussed is IL4; the disease is endometriosis.