FGB Gene (Fibrinogen Beta Chain)
Genetic and functional insights into the FGB gene, encoding the beta chain of fibrinogen, a key component in coagulation and hemostasis.
Gene Information Card
| Symbol | FGB |
|---|---|
| Full Name | Fibrinogen Beta Chain |
| Gene Type | Protein coding |
| Chromosomal Location | 4q31.3 |
| NCBI Gene ID | 2244 ncbi.nlm.nih.gov/gene/2244 |
| Ensembl ID | ENSG00000171564 |
| UniProt ID | P02675 |
| OMIM ID | 134830 |
| HGNC ID | 3662 |
| Aliases | FIBB, fibrinogen B beta chain |
Description
The FGB gene encodes the beta chain of fibrinogen, a plasma glycoprotein composed of three pairs of nonidentical polypeptide chains (A-alpha, B-beta, and gamma) linked by disulfide bonds. Fibrinogen is synthesized primarily in the liver and plays a critical role in blood coagulation: upon thrombin cleavage, fibrinogen polymerizes into fibrin, forming a stable clot. Mutations in FGB can lead to quantitative or qualitative fibrinogen disorders, including afibrinogenemia, hypofibrinogenemia, and dysfibrinogenemia, which may result in bleeding or thrombotic phenotypes.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Congenital afibrinogenemia | Biallelic loss-of-function mutations in FGB leading to absence of functional fibrinogen | OMIM #202400; ClinVar |
| Hypofibrinogenemia | Heterozygous or compound heterozygous mutations reducing fibrinogen levels | OMIM #134830; NCBI Gene |
| Dysfibrinogenemia | Missense mutations altering fibrinogen structure and function, impairing polymerization or thrombin binding | OMIM #134830; ClinVar |
| Thrombosis (venous/arterial) | Certain FGB variants (e.g., -455G>A promoter polymorphism) associated with elevated fibrinogen levels and increased thrombotic risk | NCBI Gene; PubMed |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 112.1 | High |
| Blood | 0.5 | Low |
| Bone marrow | 0.3 | Low |
| Other tissues | <0.1 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 | 98.5 | Hepatocellular carcinoma cell line; high expression |
| Huh-7 | 85.2 | Hepatoma cell line |
| K-562 | 0.2 | Chronic myeloid leukemia; low expression |
| HeLa | 0.1 | Cervical carcinoma; negligible |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.124G>A (p.Gly42Ser) | Missense | Rare | Dysfibrinogenemia; impaired fibrin polymerization |
| c.103C>T (p.Arg35Ter) | Nonsense | Rare | Afibrinogenemia; premature stop codon, loss of function |
| c.1129G>A (p.Gly377Ser) | Missense | Rare | Hypofibrinogenemia; reduced secretion |
| c.147+1G>T | Splice site | Rare | Afibrinogenemia; aberrant splicing, null allele |
Mutation functional classification
Loss of Function (LOF)
Nonsense, frameshift, and splice-site mutations leading to afibrinogenemia or hypofibrinogenemia (e.g., p.Arg35Ter, c.147+1G>T).
Gain of Function (GOF)
Not reported for FGB; gain-of-function variants are not characteristic of this gene.
Dominant Negative (DN)
Missense mutations causing dysfibrinogenemia (e.g., p.Gly42Ser) can exert dominant-negative effects by incorporating mutant chains into fibrinogen, impairing polymerization.
View complete mutation data：
Gene Ontology (GO)
Pathways
• KEGG hsa04610 – Complement and coagulation cascades
• Reactome R-HSA-140877 – Formation of Fibrin Clot (Clotting Cascade)
• Reactome R-HSA-76002 – Platelet activation
• signaling and aggregation
Protein Summary
Fibrinogen beta chain (UniProt P02675) is a 491-amino acid protein that forms the B-beta subunit of fibrinogen. It is synthesized in the liver and secreted into plasma. The beta chain contains a coiled-coil domain and a C-terminal globular domain involved in fibrin polymerization. Post-translational modifications include N-glycosylation and disulfide bond formation. The protein is essential for clot formation; defects lead to bleeding or thrombotic disorders.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| FGB Knockout HEK293 Cell Line | EDJ-KQ2950 | Human | 2244 | Details Get a Quote |
| FGB Knockout A-549 Cell Line | EDJ-KQ22713 | Human | 2244 | Details Get a Quote |
| FGB Knockout HeLa Cell Line | EDJ-KQ53219 | Human | 2244 | Details Get a Quote |
| FGB Knockout HCT 116 Cell Line | EDJ-KQ70185 | Human | 2244 | Details Get a Quote |
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