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Genetic Archaeology
GENETIC ARCHAEOLOGY // PROFILE

IL6

Interleukin 6

CHR 7
7p15.3

Overview

IL6 (Interleukin 6) is one of the most important pro-inflammatory cytokines in the human body. It orchestrates the acute inflammatory response and stimulates the production of acute-phase proteins such as CRP. In COVID-19, it is a central factor of the feared “cytokine storm.”

📍 Chromosomal Position

7p15.3 (Chromosome 7)

🧬 Gene Category

Immune System

🔬 Inheritance

Complex (polygenic)

📊 Prevalence (rs1800795)

C allele: ~40-60% (population dependent)

Function & Significance

IL6 is produced by activated immune cells (T cells, macrophages) and endothelial cells. It has several critical functions:

  • Acute-Phase Reaction: Stimulates the liver to produce CRP and other inflammatory markers
  • B Cell Activation: Promotes the differentiation of B cells into antibody-producing plasma cells
  • T Cell Differentiation: Influences the balance between regulatory and inflammatory T cells
  • Systemic Inflammation: Overproduction causes fever, fatigue, and systemic symptoms

⚠️ COVID-19 & Cytokine Storm

In severe COVID-19 cases, IL6 can rise dramatically and trigger a life-threatening cytokine storm. Drugs like Tocilizumab (IL6 receptor blocker) are used specifically to curb this overreaction.

🧬 Relevant SNPs

These genetic variants in the IL6 promoter influence how much IL6 is produced in response to inflammatory stimuli:

rs1800795
7:22725542
Allele 1

G

/

Allele 2

C

-174G>C (Main variant):
G/G: Lower IL6 baseline production
C/C: Increased IL6 production, higher CRP levels, stronger inflammatory response
G/C: Intermediate phenotype

Clinical Significance: C allele associated with increased risk for cardiovascular diseases, severe COVID-19 course, and chronic inflammatory conditions.

rs1800796
7:22725021
Allele 1

G

/

Allele 2

C

-572G>C:
C allele: Reduced IL6 expression, potentially protective in chronic inflammation.

This variant is often in linkage disequilibrium with rs1800795 and modulates its effect.

💊 Therapeutic Relevance

Tocilizumab (Actemra®) and Sarilumab are monoclonal antibodies that block the IL6 receptor. They are used for:

  • Rheumatoid Arthritis (standard therapy)
  • Severe COVID-19 with hyperinflammation
  • Systemic juvenile idiopathic arthritis
  • Giant cell arteritis

📚 Data Sources

  • OMIM: #147620 – Interleukin 6; IL6
  • dbSNP: rs1800795, rs1800796
  • ClinVar: Variants with clinical significance in inflammatory diseases
  • PubMed: Over 50,000 publications on IL6 and clinical associations

Last update: February 2026

Biological Function

Interleukin 6 is a multifunctional cytokine. It stimulates the production of acute-phase proteins (e.g., CRP) in the liver, promotes B-cell differentiation, and plays a central role in systemic inflammatory reactions. IL6 is often elevated in chronic inflammation and autoimmune diseases.

Associated Conditions

Rheumatoid Arthritis Systemic Lupus Erythematosus Crohn's Disease COVID-19 (Cytokine Storm) Chronic Inflammation Cardiovascular Diseases
Molecular Analysis

Analyzed Markers

rs1800795 Risk Factor
Pos: 7:22725542 | Alleles: G/C

-174G>C - C-allele: Increased IL6 production, stronger inflammatory response, higher CRP, associated with cardiovascular diseases and severe COVID-19 progression.

rs1800796 Protective
Pos: 7:22725021 | Alleles: G/C

-572G>C - C-allele: Reduced IL6 expression, potentially protective in chronic inflammation.