In the past few years, with the advent of genome-wide association studies (GWAS) and the detection of pathways and genes of interest in asthma (for example, PGD2-CRTH2, ORMDL3, PI3K/AKT, IL-4-IL-13-JAK-STAT-MAP kinases, adiponectin-iNOS-NF-κB, PGD2-CRTH2, IFNs-RIG, FOXC1-miR-PI3K/AKT) small RNAs that are involved in the gene regulation (microRNAs—miRNAs) have been the topic of research [12,13,14,15,16]. Here, PTGDR2 is linked to asthma.