Peroxynitrite and its precursors, superoxide (O2− •) and nitric oxide (NO) [45], [46], have been hypothesized to induce the progression to BE and EA [45], [47], [48] and it is possible that SEPP1 may act as a marker of elevated peroxynitrite production in aneuploidy and EA. The gene discussed is SELENOP; the disease is Barrett esophagus.