CTC1 Gene - CST Complex Subunit CTC1
Essential regulator of telomere maintenance and genome stability
Gene Information Card
| Symbol | CTC1 |
|---|---|
| Full Name | CST telomere maintenance complex component 1 |
| Gene Type | Protein coding |
| Chromosomal Location | 17p13.1 |
| NCBI Gene ID | 80169 ncbi.nlm.nih.gov/gene/80169 |
| Ensembl ID | ENSG00000178904 |
| UniProt ID | Q2NKJ3 |
| OMIM ID | 613129 |
| HGNC ID | 26169 |
| Aliases | C17orf68, hCTC1, AAF-44, AAF44 |
Description
The CTC1 gene encodes a component of the CST (CTC1-STN1-TEN1) complex, which is essential for telomere maintenance and genome stability. The CST complex binds to single-stranded DNA at telomeres and is involved in telomere replication, protection, and regulation of telomerase activity. Mutations in CTC1 cause Coats plus syndrome and are associated with dyskeratosis congenita and various cancers.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Coats plus syndrome | Loss-of-function mutations in CTC1 disrupt telomere maintenance, leading to telomere shortening and genomic instability, manifesting as retinal telangiectasia, intracranial calcifications, and bone abnormalities. | PMID: 22267198, 22959315 |
| Dyskeratosis congenita | CTC1 mutations impair CST complex function, causing defective telomere elongation and premature aging phenotypes including bone marrow failure and skin abnormalities. | PMID: 22959315, 23329068 |
| Cerebroretinal microangiopathy with calcifications and cysts (CRMCC) | Biallelic CTC1 mutations result in telomere dysfunction and vascular abnormalities in brain and retina. | PMID: 22267198 |
| Hepatocellular carcinoma | Somatic CTC1 mutations and altered expression contribute to telomere dysfunction and chromosomal instability in liver cancer. | COSMIC: COSM1714072 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 12.5 | Medium |
| Bone marrow | 10.2 | Medium |
| Lymph node | 9.8 | Medium |
| Spleen | 8.5 | Medium |
| Brain | 6.3 | Low |
| Liver | 5.1 | Low |
| Heart | 4.7 | Low |
| Kidney | 4.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK 293 | 14.3 | Embryonic kidney cells, high expression |
| HeLa | 11.8 | Cervical carcinoma cells |
| K562 | 10.5 | Leukemia cells |
| HepG2 | 9.2 | Hepatocellular carcinoma cells |
| A549 | 8.1 | Lung carcinoma cells |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1234C>T (p.Arg412*) | Nonsense | Rare | Premature stop codon, loss of function |
| c.1789G>A (p.Gly597Arg) | Missense | Rare | Impaired CST complex assembly |
| c.2101delC (p.Leu701Trpfs*12) | Frameshift | Rare | Truncated protein, loss of function |
| c.2965C>T (p.Arg989Trp) | Missense | Rare | Reduced telomere binding |
Mutation functional classification
Loss of Function (LOF)
Most CTC1 mutations are loss-of-function, leading to CST complex instability, telomere shortening, and genomic instability.
Gain of Function (GOF)
No gain-of-function mutations reported in CTC1.
Dominant Negative (DN)
Some missense mutations may exert dominant-negative effects by disrupting CST complex assembly.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Telomere maintenance (Reactome: R-HSA-157579)
• DNA replication (Reactome: R-HSA-69306)
• Telomere C-strand synthesis (Reactome: R-HSA-174411)
Protein Summary
CTC1 is a 1217-amino acid protein that forms the CST complex with STN1 and TEN1. It binds single-stranded DNA at telomeres and is critical for telomere replication, capping, and telomerase regulation. The protein contains multiple OB-fold domains that mediate DNA binding and protein-protein interactions. Defects in CTC1 lead to telomere dysfunction syndromes and cancer predisposition.
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