TP53 and Barrett esophagus: Studies in Barrett’s esophagus, a known risk factor for esophageal adenocarcinoma, have shown that 4N fractions greater than 6% arise in neoplastic tissue and are associated with known genomic events such as TP53 mutations (Galipeau et al., 1996; Rabinovitch et al., 2001; Barrett et al., 2003).