rs13210247 — TRAF3IP2

TRAF3IP2 rs13210247 — The Regulatory Variant That Tilts the Act1 Rheostat

The TRAF3IP2 locus on chromosome 6q21 encodes both the Act1 adaptor protein (TRAF3IP2) and an antisense long noncoding RNA (TRAF3IP2-AS1) that acts as a molecular rheostat controlling how much Act1 protein the cell produces. rs13210247 sits inside an intron of TRAF3IP2 but overlaps the TRAF3IP2-AS1 transcript — making it a regulatory variant that fine-tunes the entire IL-17 signaling axis from a position that traditional coding-variant analysis would overlook. The G allele (also designated A4165G in TRAF3IP2-AS1 numbering) was identified as part of the TRAF3IP2 psoriasis susceptibility locus in a landmark 2010 GWAS and has since been shown to carry independent mechanistic weight as a gain-of-function lncRNA variant.

The Mechanism

Act1 is the essential adaptor for IL-17 receptor signaling¹¹ essential adaptor for IL-17 receptor signaling
Act1 couples the cytoplasmic domain of the IL-17RA/IL-17RC receptor complex to TRAF6, driving NF-κB activation and inflammatory gene expression in keratinocytes, fibroblasts, and mucosal epithelium; it is also required for normal keratinocyte differentiation through the AP1 pathway. The gene sits on the minus strand, and overlapping it is TRAF3IP2-AS1, an antisense lncRNA on the plus strand. This lncRNA recruits SRSF10²² SRSF10
Serine/arginine-rich splicing factor 10, a splicing regulator that modulates IRF1 mRNA processing and expression levels when bound to TRAF3IP2-AS1, which then downregulates IRF1 — a transcription factor that drives Act1 expression. More TRAF3IP2-AS1 activity → more SRSF10 recruitment → less IRF1 → less Act1.

The rs13210247 G allele is a gain-of-function mutant³³ rs13210247 G allele is a gain-of-function mutant
In functional assays, the G variant of TRAF3IP2-AS1 shows enhanced ability to recruit SRSF10 compared to the A wild-type, amplifying suppression of the IRF1-Act1 transcriptional axis; treatment with the mouse lncRNA homolog or SRSF10 had therapeutic effects in mouse psoriasis and autoimmune encephalomyelitis models. This enhanced SRSF10 binding → reduced IRF1 → reduced Act1 expression.

How does reducing Act1 increase psoriasis risk? Act1 has a dual role in keratinocyte biology⁴⁴ dual role in keratinocyte biology
Act1/TRAF3IP2 silencing decreases early differentiation markers (KRT1, KRT10, DSC1, DSG1) while increasing late differentiation genes (SPRR2, LCE3) characteristic of psoriatic lesions; this occurs through elevated FosB and Fra1 nuclear expression via AP1 binding sites, independently of the IL-17 pathway; the authors note this paradox remains an active area of investigation. Reducing Act1 disrupts the normal keratinocyte differentiation program through AP1 pathway deregulation, producing a psoriasis-like transcriptional signature. Separately, the missense variant rs33980500 on the same haplotype disrupts Act1's TRAF6-binding domain — so two independent mechanisms (reduced Act1 quantity via rs13210247, and altered Act1 quality via rs33980500) converge on the same locus.

The Evidence

Two independent GWAS published simultaneously in Nature Genetics in 2010 established TRAF3IP2 as a major psoriasis susceptibility locus. Ellinghaus et al.⁵⁵ Ellinghaus et al.
6,487 psoriasis cases and 8,037 controls across German, Swedish, and American cohorts; combined P=2.36×10⁻¹⁰ for rs13210247 identified rs13210247 with an odds ratio of 1.69 (95% CI 1.48–1.94) for psoriasis. Huffmeier et al.⁶⁶ Huffmeier et al.
Discovery cohort of 609 German psoriatic arthritis cases + 990 controls, replicated across six European and North American cohorts confirmed rs13210247 in moderate LD (r²=0.63) with the missense variant rs33980500 — but the two SNPs are on partially distinct haplotype blocks separated by ~9.5 kb, meaning they capture overlapping but not identical disease signal.

The haplotype analysis is where rs13210247's contribution becomes clearest. A four-SNP haplotype carrying rs13196377_G + rs13190932_G + rs33980500_T + rs13210247_A carries an OR of 2.7 (P=0.0054) for psoriasis⁷⁷ OR of 2.7 (P=0.0054) for psoriasis
Haplotype analysis in independent psoriasis cohort following initial GWAS; this is the primary risk haplotype at the TRAF3IP2 locus. A second risk haplotype (rs13196377_A + rs13190932_A + rs33980500_T + rs13210247_G) carries OR=1.8 — rs33980500_T is the shared element conferring risk across both haplotypes, while rs13210247 alleles differ between the two, reflecting two distinct haplotype backgrounds at this locus.

Disease associations extend across the IL-17/autoimmune spectrum. In Chinese cohorts, rs13210247 G is strongly associated with Behçet's disease (OR=2.40, P=6.9×10⁻⁸) and Vogt-Koyanagi-Harada syndrome (OR=2.07, P=7.2×10⁻⁶)⁸⁸ rs13210247 G is strongly associated with Behçet's disease (OR=2.40, P=6.9×10⁻⁸) and Vogt-Koyanagi-Harada syndrome (OR=2.07, P=7.2×10⁻⁶)
Study of 610 BD patients, 721 VKH patients, and 1,591 controls; AG genotype frequency 11.6% in BD vs 4.8% in controls; both conditions share Th17/IL-17 pathway dysregulation with psoriasis. In autoimmune thyroid disease, the AG genotype shows significant association with both Graves' disease and Hashimoto's thyroiditis (https://pubmed.ncbi.nlm.nih.gov/40440802/⁹⁹ https://pubmed.ncbi.nlm.nih.gov/40440802/), extending the locus's relevance beyond skin and mucosa to the endocrine-immune interface.

Practical Implications

rs13210247 sits on the highest-risk psoriasis haplotype at the TRAF3IP2 locus. For carriers who also carry rs33980500_T (D10N), the combined haplotype represents the maximum TRAF3IP2 contribution to psoriatic disease risk — both the quantity of Act1 (reduced by the lncRNA variant) and the quality of Act1 signaling (disrupted TRAF6 binding) are simultaneously compromised.

The breadth of autoimmune associations (psoriasis, psoriatic arthritis, Behçet's disease, VKH syndrome, autoimmune thyroid disease) reflects the centrality of IL-17/Act1 signaling across multiple organ systems. G allele carriers should be aware that autoimmune risk is not organ-specific: a personal or family history of any IL-17-driven condition warrants vigilance across this spectrum.

Known psoriasis triggers that activate Th17 pathways deserve attention: streptococcal pharyngitis, skin trauma (Koebner phenomenon), and psoriasis-precipitating medications (beta-blockers, lithium, antimalarials, interferons). The lncRNA therapeutic angle identified by He et al. is scientifically interesting but not yet clinically actionable.

Interactions

rs13210247 is in moderate LD (r²=0.63) with rs33980500 (D10N), but the two variants are distinct — they co-occur on the high-risk haplotype but also segregate independently. rs13210247 operates at the transcriptional level (Act1 quantity via TRAF3IP2-AS1/SRSF10/IRF1), while rs33980500 operates at the protein level (Act1 TRAF6-binding capacity). Together they represent the two main disease-contributing mechanisms at this locus.

rs13196377 and rs13190932 are the other members of the four-SNP haplotype but appear to be tagging variants rather than functional drivers — they do not independently reproduce the functional effects of D10N or rs13210247.

rs12191877 (HLA-C¹⁰¹⁰ rs12191877 (HLA-C
tags HLA-Cw*0602, the dominant psoriasis susceptibility allele affecting T-cell immune tolerance) creates a dual-hit with TRAF3IP2 rs13210247: impaired self-tolerance (HLA) combined with reduced Act1 regulatory capacity. Because HLA-Cw6 is also a major predictor of biologic therapy response, combined carriers face both elevated disease risk and a pharmacogenomically distinct treatment profile.