In this study, the authors found that several X-linked miRNAs were significantly upregulated in CF monocytes, with miR-224-5p being the most prominent; furthermore, SMAD family member 4 (SMAD4), a validated target of miR-224-5p was found to be downregulated in the CF monocytes [178]. The gene discussed is SMAD4; the disease is cystic fibrosis.