CRLF2 and Allergy: At the molecular level, the evaluation of 84 genes related to asthma and allergy indicated that the lung transcriptomic baseline effect of the in utero vanilla-flavored e-cig aerosol exposure resulted in the up-regulation of four genes (Prg2, Rnase2b, Tpsb2, and Csf2, fold-change ranged from 1.7 to 2.2) and the down-regulation of two genes, Il-13 and Crlf2 (fold-change range −1.5 to −4.8) (in utero vanilla e-cig + saline versus in utero air + saline) (Figure 4D).