rs1862513 — RETN -420C>G

Promoter variant that increases resistin expression via Sp1/Sp3 transcription factor binding, elevating circulating resistin and promoting insulin resistance and inflammation

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Resistin's Hidden Switch — The Promoter Variant That Turns Up Inflammation

Resistin is an adipokine — a signaling molecule secreted primarily by macrophages in human adipose tissue — that acts as a brake on insulin action and an accelerator of inflammation. Unlike in rodents where it comes from fat cells directly, human resistin is mainly produced by macrophages infiltrating adipose tissue11 macrophages infiltrating adipose tissue
This macrophage origin makes human resistin more of an inflammatory signal than a pure metabolic hormone, linking metabolic dysfunction to chronic low-grade inflammation. The rs1862513 -420C>G polymorphism sits in the RETN gene's promoter region and acts as a molecular volume knob: the G allele turns the gene up, increasing resistin production and widening its downstream consequences for insulin sensitivity, liver fat, and cardiovascular risk.

The Mechanism

The -420 position in the RETN promoter is a binding site for two transcription factors, Sp1 and Sp322 Sp1 and Sp3
Specificity protein 1 and 3 — zinc-finger transcription factors that activate many housekeeping and metabolic genes by binding GC-rich promoter elements. The C allele at this position does not permit this binding. The G allele creates the binding motif that allows Sp1 and Sp3 to dock and drive RETN transcription. Laboratory experiments confirmed that overexpression of Sp1 or Sp3 enhanced RETN promoter activity specifically with the -420G allele33 overexpression of Sp1 or Sp3 enhanced RETN promoter activity specifically with the -420G allele
Not the -420C allele, demonstrating allele- specific promoter activation. The result is measurably higher fasting serum resistin in G allele carriers, with the GG genotype showing the highest levels. Higher resistin impairs insulin signaling in muscle and liver, promotes hepatic fat deposition, and stimulates inflammatory cytokines including TNF-alpha and IL-6.

The Evidence

The functional discovery by Osawa et al. 200444 Osawa et al. 2004
Osawa H et al. The G/G genotype of a resistin single-nucleotide polymorphism at -420 increases type 2 diabetes mellitus susceptibility by inducing promoter activity through specific binding of Sp1/3. Diabetologia, 2004 in a Japanese cohort identified the GG genotype as associated with T2DM (adjusted OR 1.97) and found it could accelerate disease onset by 4.9 years. The association with resistin levels was independently confirmed in the Framingham Offspring Study55 Framingham Offspring Study
Hivert MF et al. 2009 — 2,531 participants followed for 28 years, where the -420C/G association with plasma resistin remained significant (P = 0.0009) in combined meta-analysis, though with high heterogeneity across studies.

A 2022 meta-analysis66 2022 meta-analysis
Zhao X et al. Frontiers in Endocrinology, 2022 — 23 case-control studies, 10,651 T2DM cases and 14,366 controls found no overall T2DM association, but detected a strong age-modifying effect: in patients under 50, the GG genotype carried substantially elevated diabetes risk (OR 3.14-4.76), while in those over 50 it appeared neutral or slightly protective — a striking finding that may reflect survivor bias, population heterogeneity, or differential expression at different life stages. This age interaction warrants further study.

Beyond diabetes, the GG genotype is associated with non-alcoholic fatty liver disease77 non-alcoholic fatty liver disease
NAFLD case-control study: GG vs CC OR 2.3, 95% CI 1.1-4.8 and with colorectal and breast cancer risk in Caucasians88 colorectal and breast cancer risk in Caucasians
Meta-analysis of 9 studies (1,951 cases): dominant model OR 1.19, 95% CI 1.05-1.35, consistent with resistin's pro-inflammatory and pro-proliferative signaling properties.

Practical Actions

The most actionable finding is that GG carriers respond more strongly to dietary and pharmacological interventions that lower resistin. Two hypocaloric diet trials in obese Caucasians found that GG carriers showed significantly greater reductions99 GG carriers showed significantly greater reductions
Insulin decreased -5.6 vs -2.9 mUI/L, HOMA-IR decreased -2.5 vs -0.6, glucose decreased -7.2 vs -0.8 mg/dL; all p<0.05 in insulin, HOMA-IR, fasting glucose, and LDL-cholesterol on calorie-restricted diets compared to C allele carriers. This means that despite higher baseline insulin resistance, GG individuals gain more from dietary intervention — a clinically useful reversal of expectations.

The Toon Genome Study1010 Toon Genome Study
Tanaka S et al. 2017 — 1,981 Japanese community-dwellers demonstrated that n-3 polyunsaturated fatty acid (PUFA) intake was inversely associated with serum resistin across all genotypes, but the inverse association was strongest in GG carriers1111 strongest in GG carriers
Resistin ranged from 18.9 ng/mL in the lowest n-3 PUFA quartile to 14.5 ng/mL in the highest, p=0.001; genotype-intake interaction p=0.004, with minimal effect in CC carriers. This genotype-specific response to omega-3 intake is directly actionable.

A small pilot study also found that the GG genotype predicted greater response to pioglitazone1212 predicted greater response to pioglitazone
G/G genotype was independent predictor of FPG reduction, P=0.020, and HOMA-IR reduction, P=0.012 — a thiazolidinedione insulin sensitizer — in T2DM patients, suggesting pharmacogenomic relevance worth discussing with a prescribing physician if diabetes medications are being considered.

Monitoring serum resistin, fasting insulin, and HOMA-IR provides direct feedback on how well diet and lifestyle changes are working for GG carriers.

Interactions

The rs3219175 variant (c.-358G>A, also written as SNP-358) in the RETN promoter interacts with rs1862513. Japanese studies show that the G-A haplotype (combining -420G and -358A) produces the highest plasma resistin levels1313 highest plasma resistin levels
SNP-358 A allele is required for -420G to confer maximum resistin elevation in the Japanese population, greater than either variant alone. For those carrying GG at rs1862513, knowing the rs3219175 genotype provides additional resolution on resistin expression.

The PPARG rs1801282 Pro12Ala variant also interacts with rs1862513: in Japanese populations, PPARgamma Pro/Pro combined with -420 G/G genotype was synergistically associated with higher plasma resistin1414 PPARgamma Pro/Pro combined with -420 G/G genotype was synergistically associated with higher plasma resistin
Synergistic interaction detected in a general Japanese community study. Since PPARgamma is the primary transcription factor through which thiazolidinediones work, this interaction may partly explain the genotype-specific pioglitazone response.

Nutrient Interactions

omega-3 fatty acids (EPA/DHA) altered_metabolism

Genotype Interpretations

What each possible genotype means for this variant.

CC Baseline Resistin Production Normal

Standard resistin gene promoter activity with normal baseline resistin levels

You have two copies of the C allele at the -420 position in the RETN promoter. The Sp1/Sp3 transcription factor binding site is not activated, so your resistin gene runs at its basal rate. Your circulating resistin levels are expected to be in the lower range, and your insulin sensitivity is not specifically impaired by this promoter variant. Approximately 44% of people of European descent share this genotype.

CG Modestly Elevated Resistin Intermediate

One G allele activates partial Sp1/Sp3 binding, raising resistin levels and modestly reducing insulin sensitivity

The heterozygous state produces intermediate resistin levels — higher than CC but lower than GG. Studies in Japanese populations found that the -420G allele is an additive contributor to resistin levels, so CG individuals fall between the two homozygous groups. The age-stratified meta-analysis found that the association with type 2 diabetes is primarily evident in younger patients (under 50), where intermediate genotypes like CG may carry modestly elevated risk. Dietary omega-3 intake shows some resistin- lowering effect in CG carriers, though weaker than in GG homozygotes.

GG Elevated Resistin Production High Risk

Two G alleles drive maximum Sp1/Sp3 binding, significantly elevating resistin and promoting insulin resistance and inflammation

The GG genotype confers maximum Sp1/Sp3-driven RETN transcription, leading to chronically elevated circulating resistin. Resistin impairs insulin receptor signaling in skeletal muscle and liver, promotes hepatic glucose production, and activates inflammatory pathways including NF-kB, TNF-alpha, and IL-6 secretion. Beyond metabolic effects, elevated resistin promotes endothelial dysfunction, hepatic fat accumulation (NAFLD OR 2.3), and may contribute to cancer risk through its pro-proliferative and anti- apoptotic signaling properties.

The most clinically actionable aspect of the GG genotype is the documented genotype-specific dietary response. Two randomized hypocaloric diet trials showed GG carriers achieved significantly greater reductions in insulin (-5.6 vs -2.9 mUI/L), HOMA-IR (-2.5 vs -0.6), fasting glucose (-7.2 vs -0.8 mg/dL), and LDL-cholesterol (-13.0 vs -4.3 mg/dL) than C allele carriers. The Toon Genome Study further showed that omega-3 PUFA intake produced a significant genotype-specific reduction in resistin levels in GG individuals (18.9 to 14.5 ng/mL across intake quartiles, p=0.001), with minimal effect in CC carriers.

A small pilot study found GG genotype independently predicted better response to pioglitazone (a thiazolidinedione insulin sensitizer) for both fasting glucose and HOMA-IR reduction. If diabetes medications are under consideration, this may be worth discussing with a prescribing physician.