TBX5 and Barrett esophagus: So far, genome-wide association studies have identified four loci within or near MHC, FOXF1, GDF7, and TBX5 associated with the development of Barrett's oesophagus,7, 8 and four additional loci within or near CRTC1, BARX1, FOXP1, and ALDH1A2 associated with development of both Barrett's oesophagus and oesophageal adenocarcinoma.8, 9 However, because of small sample sizes analysed so far, these loci account for only a part of the genetic variance of Barrett's oesophagus and oesophageal adenocarcinoma.6