rs28362491 — NFKB1 -94ins/delATTG

Promoter insertion/deletion polymorphism reducing NF-κB p50 transcription and increasing cardiovascular and inflammatory disease susceptibility

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The NF-κB Switch — How a Four-Letter Deletion Shapes Your Immune and Cardiovascular Risk

Nuclear factor kappa B (NF-κB) is the master switch of the human inflammatory response. When your immune cells sense a pathogen, tissue damage, or oxidative stress, NF-κB activates dozens of genes that mount the immune defense — but it also activates inhibitory proteins (like IκBα) that eventually turn the response off. The NFKB1 gene encodes the p50 subunit, one of NF-κB's most important components. This variant, located at position -94 in the gene's promoter region11 promoter region
The promoter is the regulatory "on switch" that controls how much gene product is made, is a four-nucleotide insertion (ATTG) whose presence or absence directly controls how much p50 your cells produce. Because p50 is both pro-inflammatory and anti-inflammatory depending on context, this seemingly small genetic difference has ripple effects across cardiovascular disease, autoimmune conditions, and infection susceptibility.

The Mechanism

The -94ins/delATTG polymorphism sits at a key transcription factor binding site in the NFKB1 5′ regulatory region. The foundational functional study22 The foundational functional study
Karban et al. 2004, Human Molecular Genetics — identified this as the first potentially functional NFKB1 polymorphism demonstrated that nuclear proteins from normal human colon tissue and colonic cell lines bind specifically to the insertion allele but not to the deletion allele. Luciferase reporter assays confirmed that constructs carrying the deletion allele generate significantly less NFKB1 promoter activity than those carrying the insertion allele. In other words, the deletion allele produces less NF-κB p50 protein.

This reduction in p50 production creates a paradox: while NF-κB is often framed as a pro-inflammatory transcription factor, the p50 homodimer actually functions as a transcriptional repressor of inflammatory genes33 transcriptional repressor of inflammatory genes
p50/p50 homodimers competitively displace p50/p65 heterodimers from κB sites, suppressing transcription. Reduced p50 therefore means less negative feedback on inflammatory cytokine production. Laboratory studies using human umbilical vein endothelial cells (HUVECs) from del/del individuals show reduced Bcl-2 expression, lower NF-κB p50 protein, elevated IL-6 production, and increased susceptibility to hydrogen peroxide-induced apoptosis — a picture of both pro-inflammatory dysregulation and impaired endothelial cell survival.

The Evidence

The cardiovascular evidence is the most thoroughly characterized. A 2016 meta-analysis44 A 2016 meta-analysis
Chen et al., Genetic Testing and Molecular Biomarkers, pooling 7 case-control studies found that the del/del genotype confers OR 1.26 (95% CI 1.12–1.43) for coronary artery disease (CAD) compared to ins/ins. The ins/del heterozygous genotype showed OR 1.11 (95% CI 1.01–1.21). Effects were present in both Asian (OR 1.47, homozygote model) and Caucasian (OR 1.21) populations.

A 2019 case-control study55 A 2019 case-control study
Jin et al., Bioscience Reports — 778 ACS patients vs 1,112 controls in Chinese Han found that the del/del genotype frequency was 18.0% in ACS patients vs 14.1% in controls (P=0.009) and that del/del carriers had 1.33-fold higher ACS risk after multivariate adjustment. Del/del patients also showed significantly more severe coronary stenosis. A concurrent 2020 study66 A concurrent 2020 study
Luo et al., Scientific Reports — 359 MI patients vs 1,085 controls found the del allele frequency 41.2% vs 36.4% in controls (P=0.021), and critically, MI patients with del/del had Gensini scores (a measure of coronary stenosis burden) 32–43% higher than other genotypes, along with significantly elevated plasma IL-6 levels and higher rates of multi-vessel disease (P=0.001).

Long-term prognostic data77 Long-term prognostic data
Luo et al. 2022, BMC Cardiovascular Disorders — 257 high-risk CVD patients followed for 30 months showed MACE incidence of 32.6% in del/del vs 15.9–16.5% in II and ID carriers, with del/del carriers having approximately 2.3 times the relative risk for major adverse events after controlling for traditional cardiovascular risk factors.

Beyond cardiovascular disease, the polymorphism has been examined in autoimmune contexts. A study of rheumatoid arthritis88 A study of rheumatoid arthritis
Elkhawaga et al. 2021, Clinical Rheumatology — 196 Egyptian RA patients found that the del allele was associated with higher IL-6 levels in a dose-dependent manner: del/del carriers had 41.4 ± 16.2 pg/mL, compared to 19.1 ± 12.4 pg/mL for ins/del and 11.4 ± 4.2 pg/mL for ins/ins. Erosive arthritis was associated with combined del genotype carriers (OR 1.86). The original genetic association study99 original genetic association study
Karban et al. 2004, the foundational paper identified an association with ulcerative colitis in North American cohorts, positioning this variant as relevant across multiple inflammatory disease domains.

Practical Actions

The del/del genotype creates a substrate of elevated baseline inflammatory signaling through impaired NF-κB p50-mediated feedback suppression. The actionable strategy is to monitor cardiovascular biomarkers proactively and use dietary and targeted supplementation approaches that modulate the NF-κB and cytokine pathways this variant directly affects.

Tracking circulating IL-6 and high-sensitivity CRP directly tests the downstream consequence of this variant — elevated inflammatory cytokine production. Del/del carriers consistently show higher IL-6 in multiple studies across different disease contexts. Identifying individual elevation allows for more targeted intervention and serves as a gauge for whether dietary and supplement strategies are working.

Omega-3 fatty acids (EPA and DHA) downregulate NF-κB activation and reduce IL-6 and other downstream cytokines through lipid mediator pathways (resolvins, protectins) that directly intersect with the NF-κB signaling axis this variant impairs. Specific omega-3 supplementation at 2–3 g EPA+DHA daily has documented effects on IL-6 reduction in inflammatory disease contexts.

Interactions

The most clinically relevant interaction is with other NF-κB pathway modulators. NFKBIA (IκBα) variants — particularly in the 3′UTR — interact with NFKB1 to modulate overall NF-κB tone; rs28362491 del/del combined with NFKBIA risk genotypes may create compounded dysregulation. CARD15/NOD2 mutations in Crohn's disease have been examined alongside this variant without definitive interaction effects in European populations, though the NF-κB pathway mechanistically connects them.

Within cardiovascular risk, del/del carriers who also carry NOS3 (eNOS) variants reducing nitric oxide production face a dual hit: impaired endothelial NF-κB signaling AND reduced vasodilation capacity. The eNOS reduction seen in del/del HUVEC cells in laboratory studies (Luo 2017) suggests particular relevance for variants in rs1799983 (NOS3 Glu298Asp).

Genotype Interpretations

What each possible genotype means for this variant.

II Normal Promoter Activity Normal

Standard NF-κB p50 production and typical inflammatory regulation

You carry two copies of the insertion allele, the form associated with normal NF-κB p50 promoter activity. Functional studies show that the insertion allele supports full protein binding at the NFKB1 promoter and generates higher p50 expression. About 36% of people of European descent share this genotype. Your NF-κB p50-mediated inflammatory feedback regulation operates at baseline expected levels — this variant contributes no additional cardiovascular or inflammatory disease risk compared to ins/del or del/del carriers.

DI Reduced Promoter Activity Intermediate

Moderately reduced NF-κB p50 production and modestly elevated inflammatory risk

The heterozygous state produces a gene dosage effect: one high-activity promoter copy (insertion) and one low-activity copy (deletion) result in intermediate p50 protein levels. This partial reduction in the NF-κB transcriptional feedback brake creates a modest shift in inflammatory set point without the full dysregulation seen in del/del homozygotes.

The intermediate IL-6 levels observed across multiple studies — 19.1 pg/mL in RA patients vs 41.4 pg/mL for del/del and 11.4 pg/mL for ins/ins — illustrate a clear dose-response consistent with codominant inheritance. The cardiovascular risk increase is real but modest, and the heterozygous genotype is the most common in European populations.

Monitoring inflammatory biomarkers provides the most direct insight into whether this partial reduction in p50 activity is translating into measurable systemic inflammation in your individual context.

DD Low Promoter Activity High Risk

Significantly reduced NF-κB p50 production and elevated cardiovascular and inflammatory disease risk

The del/del homozygous state represents the maximum reduction in NF-κB p50 transcriptional activity from this variant. The functional cascade is well-characterized: reduced promoter binding → less p50 protein → impaired p50 homodimer-mediated transcriptional repression of inflammatory genes → chronically elevated inflammatory cytokine production.

IL-6 levels in del/del individuals are strikingly elevated across studies in different disease contexts: 41.4 pg/mL in RA patients vs 11.4 pg/mL for ins/ins (3.6-fold difference), and significantly elevated plasma IL-6 in myocardial infarction cohorts. Del/del MI patients also show markedly higher rates of multi-vessel coronary artery disease (P=0.001) and substantially worse Gensini scores — indicating not just higher risk for events but more extensive atherosclerosis at the time of diagnosis.

Endothelial cell studies reveal a dual mechanism: reduced eNOS (endothelial nitric oxide synthase) expression, impaired vasodilation capacity, and increased apoptotic susceptibility under oxidative stress — suggesting the variant affects both inflammatory and vascular structural integrity simultaneously.

Beyond cardiovascular disease, the del/del genotype has been linked to autoimmune susceptibility (ulcerative colitis, rheumatoid arthritis severity, pemphigus vulgaris), consistent with the role of p50 in maintaining immune homeostasis. This pattern reflects the pleiotropic role of NF-κB p50 across diverse inflammatory disease states.