Second, the existing meta-analysis covered not all the current systemic agents as eleven biologics including four TNF-α inhibitors, one IL-12/23 inhibitor, three IL-23 inhibitors and three IL-17 inhibitors have been approved for the treatment of moderate-to-severe psoriasis, and some small targeted molecules such as Janus kinase (JAK) inhibitors are investigated. The gene discussed is IL17A; the disease is psoriasis.