To our knowledge, this is the first GWAS focusing on aspirin-induced PUD; a previous GWAS in Japanese patients with duodenal ulceration, which did not stratify by aetiology, identified predisposing loci in the PSCA and ABO blood group genes [36], but not in EYA1. EYA1 and PSCA are both on chromosome 8 but are 70Mb apart, and the underlying variants are not in linkage disequilibrium. Here, ABO is linked to duodenal ulcer.