MTHFR and endometriosis: As methylation dysregulation and oxidative stress are heavily involved in endometriosis, we wanted to evaluate the prevalence of the two main MTHFR SNPs, c.677C>T and c.1298A>C, in a subpopulation of patients with stage 2+ confirmed endometriosis in a cohort of couples consulting for a history of long-standing infertility15 of multiple etiologies.