Many earlier serological studies and recent genomic studies have reported that the ABO histo-blood groups show weak but consistent associations with a large number of traits including red blood cell phenotypes [4], soluble Intercellular adhesion molecule 1 level [18], stomach cancer [19], diabetes [20], pancreatic cancer [21], and duodenal ulcer [22], together implying the possibility that this gene has a pleiotropic effect. This evidence concerns the gene ABO and duodenal ulcer.