Thus, it is believed that DP2, and to some extent also DP1, crucially contribute to various pathologies that involve eosinophils, and provide novel therapeutic approaches to conditions such as asthma, allergic rhinitis, conjunctivitis, esophagitis and skin disease, nasal polyposis, aspirin-intolerance, Crohn’s disease, and certain types of cancer. This evidence concerns the gene PTGDR and conjunctivitis.