rs4220
Variant in the FGB gene (Fibrinogen Beta Chain)
rs4220 is a single nucleotide polymorphism (SNP) in the FGB gene, involved in fibrin formation. Variants at this position have been studied in relation to immune function, metabolism, and chronic illness.
This page is for educational and informational purposes only. Not a diagnostic tool. Always consult a qualified healthcare provider.
What is the rs4220 variant?
rs4220 is a SNP (single nucleotide polymorphism) in the FGB (Fibrinogen Beta Chain) gene. It belongs to the Coagulation category and is part of the Coagulation & Vascular biological cluster. FGB encodes the beta chain of fibrinogen. The FGB promoter variant -455G>A (rs1800790) increases fibrinogen plasma levels and is associated with cardiovascular disease risk. Fibrinogen beta also participates in platelet-fibrinogen interactions.
Biological role and pathway
This variant sits within the FGB gene, which is involved in the fibrin formation pathway. Genes within the Coagulation & Vascular cluster work together to maintain balanced function across interconnected biological systems.
Variants in genes within this pathway may influence an individual's predisposition to altered function — particularly under conditions of physiological stress such as viral infection or prolonged illness.
rs4220 and Long COVID / ME-CFS research
Elevated fibrinogen levels in Long COVID patients may reflect both acute phase response and procoagulant states. FGB -455G>A increases baseline fibrinogen levels, potentially contributing to hypercoagulability and the fibrin microclot burden in Long COVID.
This information is based on published research and does not constitute medical advice. See references below.
Parent gene: FGB
rs4220 is one of 3 known variants in the FGB gene. To understand the full biological context of this variant, explore the parent gene page.
View FGB gene page →Conditions studied in relation to rs4220
Research into FGB variants including rs4220 has explored associations with the following conditions. These are areas of scientific investigation and do not imply causation.
Genetic insights from DNA data
Consumer DNA files from 23andMe, AncestryDNA, and MyHeritage contain raw SNP data. When you upload your file to ChronicDNA, the analysis engine checks your genotype against a curated panel of 80+ genes selected for their relevance to Long COVID, ME/CFS, and connected biological pathways - some of which may include FGB and the rs4220 variant.
The report is educational - it explains which variants you carry, what the research says about them, and how they fit into the biological pathways most relevant to chronic illness. Results are presented in plain English with appropriate scientific context, no medical jargon, no scare tactics. All results should be discussed with a qualified healthcare provider.
Other variants in the FGB gene
The following variants in FGB are also studied in relation to chronic illness and may be analysed together for a more complete picture.
Frequently asked questions
What is the rs4220 variant in the FGB gene?
rs4220 is a single nucleotide polymorphism (SNP) located in the FGB (Fibrinogen Beta Chain) gene, which is involved in fibrin formation. FGB encodes the beta chain of fibrinogen. The FGB promoter variant -455G>A (rs1800790) increases fibrinogen plasma levels and is associated with cardiovascular disease risk. Fibrinogen beta also participates in platelet-fibrinogen interactions.
How may the rs4220 variant relate to Long COVID or ME/CFS?
Elevated fibrinogen levels in Long COVID patients may reflect both acute phase response and procoagulant states. FGB -455G>A increases baseline fibrinogen levels, potentially contributing to hypercoagulability and the fibrin microclot burden in Long COVID.
Can a consumer DNA test detect the rs4220 variant?
Many consumer DNA tests such as 23andMe, AncestryDNA, and MyHeritage genotype common SNPs. ChronicDNA analyses your raw DNA file and reports on variants studied in relation to chronic illness, immune function, and metabolism. This is not a diagnostic service — results are informational and educational only.
Find out if you carry the rs4220 variant
Upload your DNA data from 23andMe, AncestryDNA, or MyHeritage and receive a personalised report covering >80 genes relevant to Long COVID and ME/CFS.
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References
The following publications were used in compiling the research context for FGB and its variants. This is not an exhaustive literature review.
- [1]PMID: 26785756
- [2]Blood
- [3]Arteriosclerosis Thrombosis and Vascular Biology