FCGR3B
Fc Gamma Receptor IIIb (CD16b)
Gene Information Card
| Symbol | FCGR3B |
|---|---|
| Full Name | Fc Gamma Receptor IIIb (CD16b) |
| Gene Type | protein-coding |
| Chromosomal Location | 1q23.3 |
| NCBI Gene ID | 2215 ncbi.nlm.nih.gov/gene/2215 |
| Ensembl ID | ENSG00000162747 |
| UniProt ID | O75015 |
| OMIM ID | 146640 |
| HGNC ID | 3620 |
| Aliases | CD16b, FCG3, FCGR3, FCR-10, IGFR2 |
Description
FCGR3B encodes the low-affinity Fc gamma receptor IIIb (CD16b), a glycosylphosphatidylinositol (GPI)-anchored protein expressed predominantly on neutrophils. It binds IgG immune complexes and plays a critical role in immune complex clearance, neutrophil activation, and antibody-dependent cellular cytotoxicity (ADCC). Genetic variation in FCGR3B is associated with susceptibility to autoimmune diseases, particularly systemic lupus erythematosus (SLE) and glomerulonephritis.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Systemic Lupus Erythematosus (SLE) | Copy number variation (CNV) leading to reduced FCGR3B expression impairs immune complex clearance, increasing autoantibody deposition and inflammation. | OMIM #146640; NCBI Gene PMID: 12469122 |
| Glomerulonephritis | Low FCGR3B copy number is associated with increased risk of lupus nephritis due to defective neutrophil-mediated clearance of immune complexes. | OMIM #146640; ClinVar |
| Autoimmune Neutropenia | Anti-neutrophil antibodies targeting CD16b can cause neutrophil destruction, leading to neutropenia. | OMIM #146640; PMID: 10482962 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Whole Blood | 45.2 | High |
| Spleen | 12.8 | Medium |
| Bone Marrow | 8.5 | Medium |
| Lung | 3.1 | Low |
| Liver | 0.5 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| Neutrophils | 120.0 | Primary cell type |
| Monocytes | 15.3 | Low expression |
| NK cells | 2.1 | Very low (FCGR3A predominant) |
| HL-60 (neutrophil-like) | 55.0 | Differentiated cells |
| U937 (monocytic) | 8.0 | Low |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| NA1/NA2 polymorphism | SNP (rs403016, rs447536) | Polymorphic (50% Caucasian) | Alters glycosylation and IgG binding affinity; NA2 associated with lower immune complex clearance and SLE risk. |
| CNV (copy number variation) | Structural variant | Variable (0-4 copies) | Low copy number (<2) increases SLE and glomerulonephritis risk; high copy number may protect. |
| c.233C>T (p.Ala78Val) | Missense | Rare (<0.1%) | Reported in ClinVar as likely benign; functional impact unclear. |
Mutation functional classification
Loss of Function (LOF)
Reduced FCGR3B copy number (CNV) leads to decreased protein expression on neutrophils, impairing immune complex clearance and increasing autoimmunity risk.
Gain of Function (GOF)
High copy number (≥3) may enhance immune complex clearance, potentially protective against SLE but not clearly documented as pathogenic.
Dominant Negative (DN)
No dominant-negative mutations reported for FCGR3B.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Fc gamma R-mediated phagocytosis (KEGG hsa04666)
• Immune complex clearance (Reactome R-HSA-2029481)
• Neutrophil degranulation (Reactome R-HSA-6798695)
Protein Summary
FCGR3B encodes CD16b, a GPI-anchored low-affinity Fc gamma receptor expressed on neutrophils. It binds IgG immune complexes and mediates neutrophil activation, degranulation, and immune complex clearance. The protein is heavily glycosylated and exists as two major allotypes (NA1 and NA2) with different binding affinities. Copy number variation is a key genetic determinant of disease susceptibility, particularly in systemic lupus erythematosus and glomerulonephritis.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| FCGR3B Knockout HEK293 Cell Line | EDJ-KQ50269 | Human | 2215 | Details Get a Quote |
| FCGR3B Knockout HeLa Cell Line | EDJ-KQ53212 | Human | 2215 | Details Get a Quote |
| FCGR3B Knockout A-549 Cell Line | EDJ-KQ61693 | Human | 2215 | Details Get a Quote |
| FCGR3B Knockout HCT 116 Cell Line | EDJ-KQ70179 | Human | 2215 | Details Get a Quote |
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