TNF and psoriasis: Most of these pharmacogenetics studies are candidate gene based, focusing on polymorphisms in genes known to be involved in psoriasis susceptibility or immune system such as TNF-α signaling pathways, including TNF, TNF receptor superfamily member 1A (TNFRSF1A), TNFRSF1B, TNF-α-induced protein 3 (TNFAIP3), IL12B/IL23R, CARD14, LCE, HLA-Cw6 and so on (Vasilopoulos et al., 2012; Gallo et al., 2013; Batalla et al., 2015; Coto-Segura et al., 2016; Liu et al., 2016; Ovejero-Benito et al., 2017; Dand et al., 2019; van den Reek et al., 2017; Song et al., 2015).