The majority of studies of endometriosis to date have focused on dioxin-like PCBs (coplanar PCBs that induce biologic effects through binding to the aryl hydrocarbon receptor) and have generally found no association with endometriosis (De Felip et al. 2004; Fierens et al. 2003; Heilier et al. 2007; Niskar et al. 2009; Pauwels et al. 2001; Reddy et al. 2006). The gene discussed is AHR; the disease is endometriosis.