rs6920220 — TNFAIP3

TNFAIP3 6q23 — The Upstream Regulator of Your Immune Brake

Approximately 185 kilobases upstream of the TNFAIP3 gene sits a regulatory region that controls how much A20 protein your immune cells produce. A20, encoded by TNFAIP3¹¹ A20, encoded by TNFAIP3
TNFAIP3 stands for TNF Alpha Induced Protein 3; A20 is its common protein name and a key negative regulator of NF-kB signaling is the primary brake on NF-kB-driven inflammation — the pathway that amplifies immune responses after infection or injury. The rs6920220 variant resides in an intergenic region between OLIG3 and TNFAIP3 at chromosome 6q23.3, and the A allele reduces TNFAIP3 transcription²² reduces TNFAIP3 transcription
CRISPR-Cas9 editing demonstrated that rs6920220 A-allele cells show significant downregulation of TNFAIP3 mRNA compared to G-allele controls, allowing inflammatory signals to persist longer and reach higher intensities than they should.

The Mechanism

The 6q23 intergenic region around rs6920220 contains putative transcriptional regulatory elements. Luciferase reporter assays³³ Luciferase reporter assays
In vitro functional studies using reporter constructs in T lymphoblastoid cell lines demonstrated repressor activity at rs6920220 and two neighboring SNPs in high linkage disequilibrium, confirming that this region actively modulates TNFAIP3 gene expression. When the A allele is present, this repressor activity is altered, and TNFAIP3 mRNA levels fall.

The downstream consequences are measurable: CRISPR-engineered salivary gland epithelial cells⁴⁴ CRISPR-engineered salivary gland epithelial cells
Cells with the A allele introduced by CRISPR showed markedly increased NF-κB mRNA levels, elevated IL-6 and IL-8 expression, and increased IL-1β in co-culture with immune cells. Since A20 normally terminates NF-kB signaling after immune activation, reduced A20 expression means inflammatory cascades run longer and produce more cytokines before shutting down. This is mechanistically distinct from the missense variant rs2230926 (F127C), which reduces A20 enzymatic activity — rs6920220 reduces how much A20 is made in the first place.

The Evidence

The rs6920220 A allele was first linked to rheumatoid arthritis through the Wellcome Trust Case Control Consortium GWAS⁵⁵ Wellcome Trust Case Control Consortium GWAS
Discovery was in a genome-wide association study subsequently replicated in independent cohorts and achieved unequivocal replication with P=1.1×10⁻⁸ and OR=1.22 (95% CI 1.15-1.33). A meta-analysis of 21 case-control studies⁶⁶ meta-analysis of 21 case-control studies
Included stratified analysis by ethnicity confirming Caucasian-specific effect confirmed OR 1.36 (95% CI 1.24–1.50, P<0.001) for homozygous AA carriers versus GA+GG in the overall analysis, with stratified analysis showing Caucasian-specific risk (OR 1.37, 95% CI 1.24–1.51 in the recessive model). There is no significant RA association in East Asian populations for this SNP, in contrast to other 6q23 variants.

At 6q23, rs6920220 is one of three independent RA risk signals⁷⁷ three independent RA risk signals
Conditional logistic regression identified three independent associations at 6q23: rs6920220 (risk), rs13207033 (protective), and rs5029937 (risk). Carrying both A alleles of rs6920220 and rs5029937 while lacking the protective allele of rs13207033 raises the combined OR to 1.86, substantially amplifying the individual effects.

The variant is associated with faster radiological joint destruction⁸⁸ faster radiological joint destruction
Median Larsen radiological damage scores 31 (GG) vs 36 (GA/AA), P=0.02, in autoantibody-positive RA, specifically in autoantibody-positive patients — suggesting this variant exacerbates the inflammatory joint damage characteristic of seropositive disease.

Associations extend beyond RA: rs6920220 was associated with SLE⁹⁹ rs6920220 was associated with SLE
Two independent signals near TNFAIP3 included rs6920220 with P=0.03, confirming shared autoimmune susceptibility across conditions in an Italian cohort with OR 1.53 for SLE and OR 1.69 for primary Sjogren's syndrome. The variant also conferred JIA risk¹⁰¹⁰ conferred JIA risk
OR 1.30 (95% CI 1.05-1.61), P=0.015, particularly for oligoarticular JIA, confirming its shared autoimmune susceptibility across conditions with pediatric onset.

The variant shows striking population stratification¹¹¹¹ population stratification
A allele frequency 21% in Europeans, 0.2% in East Asians, 11% in Africans by dbSNP/ALFA consortium data: high frequency in Europeans, low in East Asians. RA associations with rs6920220 are confirmed in European populations but not Asian populations, which carry the A allele at less than 0.3% frequency.

Practical Implications

If you carry one or two A alleles, your cells produce somewhat less A20 protein — the primary brake on NF-kB inflammatory signaling. This creates a genetically primed state for inflammatory amplification when immune triggers arise. For most carriers, this manifests as modestly elevated risk for autoimmune diseases rather than active disease.

The most clinically actionable implication involves anti-TNF biologic therapy. For carriers who develop autoimmune conditions — particularly rheumatoid arthritis — preliminary evidence from psoriatic arthritis cohorts¹²¹² preliminary evidence from psoriatic arthritis cohorts
Spanish PsA cohort (n=20) found rs6920220 significantly associated with quality of life improvement at 3 and 6 months with TNF inhibitor treatment suggests this variant may influence how well TNF inhibitors work. The biological logic is coherent: since reduced A20 drives excess NF-kB activity and the TNF signaling pathway feeds directly into NF-kB, blocking TNF upstream could be particularly relevant for carriers. However, this evidence is from a small cohort and should be treated as emerging rather than established guidance. Sharing your genotype with your rheumatologist provides useful context when selecting between biologics with different mechanisms.

The variant's association with more severe radiological damage in autoantibody-positive RA (higher Larsen scores) underscores the value of early and aggressive treatment for A-allele carriers who develop seropositive disease.

Interactions

rs6920220 is one of three independent association signals at the 6q23 locus. The other two variants — rs5029937 (intronic in TNFAIP3, also risk-conferring) and rs13207033 (protective) — are independently inherited and their combined effect can substantially raise or lower RA risk beyond rs6920220 alone.

The TNFAIP3 missense variant rs2230926 (F127C) impairs A20 enzymatic activity through a completely independent mechanism: rs6920220 reduces how much A20 is made; rs2230926 makes A20 less effective at its job. Carriers of both the rs6920220 A allele and rs2230926 G allele could have both impaired A20 expression and impaired A20 function, representing compounded NF-kB dysregulation.

PTPN22 R620W (rs2476601) and TNF-alpha -308 (rs1800629) define the broader genetic context for autoimmune and anti-TNF response risk — each operating through distinct mechanisms that converge on T-cell activation and inflammatory amplification.