Aspirin is associated with an increased risk of bleeding and gastrointestinal lesions, such as mucosal erosions and ulcers (25); the gastrointestinal toxicity of aspirin is primarily attributed to the inhibition of COX-1 and COX-2 in the gastrointestinal mucosa, which impairs the physiological role of prostanoids in mucosal cytoprotection and tissue repair. Here, PTGS1 is linked to ulcer disease.