PDE4B and asthma: In summary, our study took advantage of our previously published evaluation of nasal epithelial cell-derived RNA from asthmatic and non-allergic children [6], population differences in asthma prevalence, tagging SNPs in the HapMap database, and the published literature to identify six genes (ADCY2, DNAH5, KIF3A, PDE4B, PLAU, SPRR2B) for detailed and targeted genetic testing.