Table 2.

Genes associated with juvenile idiopathic arthritis’s monogenic forms.

Genes	Causal mutations	Related subtype of JIA	Functional evidence	Mechanism	Citations
LACC1	p.Cys284Arg, p.ILe254Val, rs3816311, p.Arg414Ter, p.Ile330del, p.CYs43Tyrfs*6	Systemic JIA	The TNF levels in LACC1/mice were elevated. In macrophages and dendritic cells, LPS and other TLR ligands increased LACC1 transcripts and protein levels	Regulation of inflammation	[19–22]
LRBRA	–	Oligoarthritis	High quantities of serum and secretory IgA are produced by LRBA/mice	Peripheral tolerance issues	[23]
UNCD13	c.117 + 143A>G 753 + 3 [G>A], 1579 [C>T] R527W	Systemic JIA	Human effector CD8 + T lymphocytes and developed NK cells both showed high levels of Munc13-4 expression. Upon cytotoxic lymphocyte differentiation, the expression of Munc13-4 was specifically increased	Disrupting the binding of transcription factors	[24–26]
NFIL3	p.M170I	Systemic JIA	Mutations in NFIL3 cause increased IL-1	Irritation for arthritis. IL-1 overproduction during innate immune system development	[27]

IgA = immunoglobulin A, IL-1 = interleukin 1, JIA = juvenile idiopathic arthritis, LACC1 = laccase domain containing 1, LPS = lipopolysaccharide, LRBA = LPS-responsive beige-like anchor protein, MUNC13-4 = mammalian Unc-13 homolog D, NFIL3 = nuclear factor, interleukin 3 regulated, NK = natural killer cells, TLR = Toll-like receptor, TNF = tumour necrosis factor, UNC13 = unc-13 homolog.