IL-12 drives the differentiation of naive T cells into interferon-γ (IFN-γ)-producing T helper 1 (Th1) cells and, without a doubt, research into therapies targeting the IL12/IL23 signaling pathway, such as for anti-IL-12p40 ustekinumab, a promising treatment in psoriasis and Crohn disease, but unsuccessful in sarcoidosis, will be important for the management of patients sharing specific polymorphisms in these genes [74]. The gene discussed is IL23A; the disease is sarcoidosis.