FCN2 Gene - Ficolin-2
Key Pattern Recognition Molecule in the Lectin Complement Pathway
Gene Information Card
| Symbol | FCN2 |
|---|---|
| Full Name | Ficolin-2 |
| Gene Type | Protein coding |
| Chromosomal Location | 9q34.3 |
| NCBI Gene ID | 2220 ncbi.nlm.nih.gov/gene/2220 |
| Ensembl ID | ENSG00000160339 |
| UniProt ID | Q15485 |
| OMIM ID | 601624 |
| HGNC ID | 3624 |
| Aliases | Ficolin-2, L-ficolin, P35, ficolin B, FCNB, hucolin |
Description
The FCN2 gene encodes ficolin-2 (also known as L-ficolin), a soluble pattern recognition molecule of the innate immune system. Ficolin-2 is primarily produced in the liver and secreted into the bloodstream. It recognizes carbohydrate moieties (specifically N-acetylglucosamine) and acetylated groups on microbial surfaces, activating the lectin complement pathway via mannose-binding lectin-associated serine proteases (MASPs). FCN2 polymorphisms influence serum ficolin-2 levels and have been associated with susceptibility to various infectious and inflammatory diseases.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Recurrent respiratory infections | FCN2 deficiency leads to impaired lectin pathway activation and opsonization of pathogens | ClinVar, PMID: 22112314 |
| Invasive pneumococcal disease | Low ficolin-2 levels reduce complement-mediated clearance of Streptococcus pneumoniae | PMID: 21931326 |
| Preterm birth / neonatal sepsis | FCN2 polymorphisms associated with low ficolin-2 levels increase risk of neonatal sepsis | PMID: 22903765 |
| Leprosy | FCN2 variants influence susceptibility to Mycobacterium leprae infection | PMID: 23152761 |
| Systemic lupus erythematosus (SLE) | FCN2 polymorphisms may alter clearance of apoptotic cells and immune complexes | PMID: 23273565 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 45.2 | High |
| Spleen | 3.1 | Low |
| Lung | 2.5 | Low |
| Kidney | 1.8 | Low |
| Bone marrow | 1.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 (hepatocellular carcinoma) | 62.0 | High expression; liver-derived cell line |
| Huh-7 (hepatoma) | 55.3 | High expression |
| THP-1 (monocyte) | 0.8 | Low expression; not primary source |
| A549 (lung carcinoma) | 0.5 | Very low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| rs7851696 (G>A, p.Ala258Thr) | Missense | Allele frequency ~0.15 (1000 Genomes) | Reduced ficolin-2 binding to GlcNAc; associated with lower serum levels |
| rs17549193 (C>T, promoter) | Promoter variant | Allele frequency ~0.10 | Decreased promoter activity and lower ficolin-2 levels |
| rs3124954 (A>G, promoter) | Promoter variant | Allele frequency ~0.35 | Increased promoter activity and higher ficolin-2 levels |
Mutation functional classification
Loss of Function (LOF)
Homozygous or compound heterozygous loss-of-function variants (e.g., frameshift, nonsense) are extremely rare; no complete FCN2 deficiency has been reported in large cohorts.
Gain of Function (GOF)
Not described for FCN2.
Dominant Negative (DN)
Not described for FCN2.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Lectin complement pathway (Reactome: R-HSA-166663)
• Innate immune system (Reactome: R-HSA-168249)
• Complement cascade (KEGG: hsa04610)
Protein Summary
Ficolin-2 (L-ficolin) is a 35 kDa serum protein composed of a collagen-like domain and a fibrinogen-like domain. It forms oligomers (mainly tetramers) that recognize acetylated sugars and other microbial patterns. Upon binding, it activates the lectin complement pathway through MASP-1 and MASP-2, leading to C4 and C2 cleavage and downstream opsonization and lysis of pathogens. Ficolin-2 also acts as an opsonin directly, enhancing phagocytosis. Serum levels vary widely (0.5–12 μg/mL) and are influenced by FCN2 promoter polymorphisms.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| FCN2 Knockout HEK293 Cell Line | EDJ-KQ4582 | Human | 2220 | Details Get a Quote |
| FCN2 Knockout HeLa Cell Line | EDJ-KQ53214 | Human | 2220 | Details Get a Quote |
| FCN2 Knockout A-549 Cell Line | EDJ-KQ61695 | Human | 2220 | Details Get a Quote |
| FCN2 Knockout HCT 116 Cell Line | EDJ-KQ70182 | Human | 2220 | Details Get a Quote |
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