C1QC Gene - Complement C1q C Chain
Key component of the classical complement pathway; associated with immune deficiency and autoimmune disorders
Gene Information Card
| Symbol | C1QC |
|---|---|
| Full Name | Complement C1q C Chain |
| Gene Type | Protein coding |
| Chromosomal Location | 1p36.12 |
| NCBI Gene ID | 714 ncbi.nlm.nih.gov/gene/714 |
| Ensembl ID | ENSG00000159189 |
| UniProt ID | P02747 |
| OMIM ID | 120550 |
| HGNC ID | 1242 |
| Aliases | C1QG, C1QC_HUMAN |
Description
C1QC encodes the C chain of complement C1q, a 22-chain protein (6A, 6B, 6C) that initiates the classical complement pathway. C1q binds to immune complexes and pathogens, triggering proteolytic cascades for opsonization and lysis. Mutations in C1QC cause C1q deficiency, strongly linked to systemic lupus erythematosus (SLE) and recurrent infections.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| C1q deficiency | Loss-of-function mutations in C1QC prevent C1q assembly, impairing clearance of apoptotic cells and immune complexes | OMIM #613652; ClinVar pathogenic variants |
| Systemic lupus erythematosus (SLE) | C1q deficiency leads to defective apoptotic debris clearance, promoting autoimmunity and SLE | Multiple case reports; OMIM 120550 |
| Recurrent pyogenic infections | Impaired classical pathway reduces opsonization of encapsulated bacteria | ClinVar; literature review |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 12.5 | Medium |
| Spleen | 8.2 | Medium |
| Lung | 6.1 | Low |
| Kidney | 4.3 | Low |
| Heart | 2.0 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 | 15.3 | Hepatocyte line; high expression |
| THP-1 | 9.8 | Monocyte line; moderate expression |
| A549 | 3.2 | Lung epithelial; low expression |
| K562 | 1.1 | Erythroleukemia; not detected |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.154C>T (p.Arg52*) | Nonsense | Rare | Loss of function; truncated protein |
| c.202G>A (p.Gly68Arg) | Missense | Rare | Impaired C1q assembly |
| c.1A>G (p.Met1?) | Start loss | Rare | No protein production |
Mutation functional classification
Loss of Function (LOF)
Nonsense, frameshift, and start-loss mutations in C1QC abolish C1q C chain synthesis, preventing formation of functional C1q heterotrimer.
Gain of Function (GOF)
Not reported for C1QC.
Dominant Negative (DN)
Not reported; C1q deficiency is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Complement cascade (classical pathway) - Reactome R-HSA-166663
• Complement and coagulation cascades - KEGG hsa04610
Protein Summary
C1QC encodes the C chain of complement C1q, a 245-amino acid protein (UniProt P02747) containing a collagen-like domain and a globular C1q domain. The C chain assembles with A and B chains to form the C1q heterotrimer, which binds to Fc regions of IgG/IgM and initiates the classical complement pathway. The protein is primarily secreted by macrophages, dendritic cells, and hepatocytes.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| C1QC Knockout HEK293 Cell Line | EDJ-KQ50163 | Human | 714 | Details Get a Quote |
| C1QC Knockout HeLa Cell Line | EDJ-KQ52742 | Human | 714 | Details Get a Quote |
| C1QC Knockout A-549 Cell Line | EDJ-KQ61214 | Human | 714 | Details Get a Quote |
| C1QC Knockout HCT 116 Cell Line | EDJ-KQ69706 | Human | 714 | Details Get a Quote |
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