The prostaglandin D2 (PGD2) receptor CRTH2 (chemoattractant receptor homologous molecule expressed on T helper type 2 (Th2) cells) appears to play a pivotal role in allergic diseases by influencing migration of inflammatory cells such as eosinophils, basophils and Th2 cells [1]–[8]. Here, PTGDR2 is linked to allergic disease.