Table 1.

Associations of gene polymorphisms with susceptibility to Ps, PsA and RA as well as response to treatment

Gene	Gene function	Genetic variant	Associations	References
TNFR1B	TNF receptor superfamily 1B; binds tumor necrosis factor involved in apoptosis and inflammation, proliferation, survival, and differentiation	rs1061622	Positive response to etanercept, poor response to infliximab and adalimumab in Ps	Vasilopoulos 2012 [25]
TNFAIP3	TNF-α induced protein 3 gene; expression rapidly induced by TNF, inhibits NF-κB activation, TNF-mediated apoptosis, critical for limiting inflammation by terminating TNF-induced NF-κB responses	rs2230926	Positive response to anti-TNF in Ps	Tejasvi 2012 [26]
		rs610604	No association with response to ustekinumab in Ps	Talamonti 2013 [30]
IL-12B	Ligand IL23R Differentiation of Th1 cells; stimulation of INF-γ and TNF-α production; expansion and maintenance of Th17 cells	rs3212227	Ps Early onset of Ps PsA PsA, Ps	Cargil 2007 [15], Capon 2007 [14], Indhumanthi 2016 [16], Nair 2008 [31] Smith 2008 [32] Filer 2008 [33] Liu 2008 [34], Li 2009 [35]
		rs6887695	Ps PsA PsA, Ps	Cargil 2007 [15], Capon 2007 [14], Smith 2008 [32], Nair 2008 [31], Filer 2008 [33], Liu 2008 [34] Li 2009 [35]
IL-13	Genetic variations may result in deregulation of the Th1 and Th17 pathways, involved in B-cell differentiation	rs20541	Ps PsA ↑ PsA in Ps PsA	Chang 2008 [36] Duffin 2009 [37]; Eder 2011 [38] Bowes 2011 [39]
		rs848	PsA ↑ PsA in Ps PsA	Duffin 2009 [37] Eder 2011 [38] Bowes 2011 [39]
		rs1800925	Ps, RA ↑ PsA in Ps PsA	Li 2009 [35] Eder 2011 [38] Bowes 2011 [39]
IL-23R	Receptor of IL-23, hyperproliferation of psoriatic skin, expansion and maintenance of Th17 cells, promoter of chronic inflammation in RA, IL-23 inhibits the development of Treg cells, necessary for differentiation of Th17	rs7530511	Early onset of Ps Ps PsA RA, PsA	Smith 2008 [32] Nair 2008 [31] Filer 2008 [33] Li 2009 [35]
		rs11209026	Early onset of Ps Ps PsA	Smith 2008 [32] Nair 2008 [31]; Filer 2008 [33]
		rs2201841	Ps RA	Indhumanthi 2016 [16] Farago 2008 [40]
IL-1B	Mediator of the inflammatory response, inhibits Treg cells, necessary for differentiation of Th17	rs16944	Ps, PsA RA	Reich 2002 [41] Tolusso 2006 [42]
		rs1143634	Ps, PsA RA	Reich 2002 [41] Tolusso 2006 [42]
IL-10	Inhibits Th1 differentiation, promoting Treg differentiation	rs1800896	Ps RA Response to anti-TNF in RA	Baran 2008 [43] Lee 2012 [44] Liu 2008 [45]
		rs1800871	Ps	Baran 2008 [43]
		rs1800872	Ps RA	Baran 2008 [43] Lee 2012 [44]
IL-21	Increased hyperproliferation of psoriatic skin, increased mononuclear inflammation	rs6822844	RA Ps, PsA	Zhernakova 2007 [46] Schrodi 2008 [47]
TNF	Mediates numerous inflammatory and immunoregulatory activities	rs1800629 (–308G>A)	Genotype AA – poor response to etanercept in RA Genotype AG – a reduced risk of Ps	Maxwell 2008 [28] Li 2007 [17]
		rs361525 (–238G>A)	Genotype GA – poor response to infliximab in RA and an increased risk of Ps	Maxwell 2008 [28] Li 2007 [17]
		rs1799724	Positive response to etanercept, poor response to infliximab and adalimumab in Ps	Vasilopoulos 2012 [25]
HLA-C	Belongs to the MHC class I receptors, expressed in nearly all cells, and present small peptides to the immune system, HLA-C is a locus on chromosome 6, which encodes for a large number of HLA-C alleles that are class-I MHC receptors	rs10484554	Positive response to adalimumab in Ps, poor response to ustekinumab in Ps	Masouri 2016 [29]
IL-17R	IL-17 receptor binds interleukin 17A, protects against extracellular pathogens, but conversely promotes inflammatory pathology in autoimmune diseases	rs4819554	Positive response to anti-TNF in Ps	Batalla 2018 [24]
ERAP1	Endoplasmic reticulum aminopeptidase 1, encoded protein is an aminopeptidase involved in trimming HLA class I-binding precursors so that they can be presented on MHC class I molecules	rs151823	Positive response to ustekinumab in Ps	Masouri 2016 [29]
		rs26653	Positive response to ustekinumab in Ps	Masouri 2016 [29]