TTC8: Tetratricopeptide Repeat Domain 8
A gene associated with Bardet-Biedl syndrome and retinal degeneration
Gene Information Card
| Symbol | TTC8 |
|---|---|
| Full Name | Tetratricopeptide Repeat Domain 8 |
| Gene Type | protein-coding |
| Chromosomal Location | 14q31.3 |
| NCBI Gene ID | 123687 ncbi.nlm.nih.gov/gene/123687 |
| Ensembl ID | ENSG00000165533 |
| UniProt ID | Q8TBP5 |
| OMIM ID | 608132 |
| HGNC ID | 20087 |
| Aliases | BBS8, RP51, TTC8A, TTC8B |
Description
TTC8 (tetratricopeptide repeat domain 8) encodes a protein containing tetratricopeptide repeats (TPR) that is involved in ciliary assembly and function. It is a component of the BBSome complex, which is essential for ciliary membrane trafficking. Mutations in TTC8 cause Bardet-Biedl syndrome type 8 (BBS8) and are also associated with non-syndromic retinitis pigmentosa (RP51).
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Bardet-Biedl syndrome 8 (BBS8) | Loss of function of TTC8 disrupts BBSome complex assembly, impairing ciliary transport and leading to ciliopathy phenotypes | OMIM #615985 |
| Retinitis pigmentosa 51 (RP51) | Biallelic TTC8 mutations cause photoreceptor degeneration due to defective ciliary trafficking in retinal cells | OMIM #613464 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 12.3 | Medium |
| Retina | 10.1 | Medium |
| Brain (cerebellum) | 8.5 | Medium |
| Kidney | 6.2 | Low |
| Lung | 4.8 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| ARPE-19 (retinal pigment epithelium) | 9.7 | Retinal cell line |
| HEK 293 (embryonic kidney) | 7.4 | Common model |
| HeLa (cervical carcinoma) | 5.1 | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.118G>A (p.Gly40Arg) | Missense | Rare | Disrupts TPR domain, reduces BBSome binding |
| c.430C>T (p.Arg144*) | Nonsense | Rare | Premature stop, loss of function |
| c.1040_1041del (p.Glu347Valfs*2) | Frameshift | Rare | Truncated protein, no functional BBSome |
Mutation functional classification
Loss of Function (LOF)
Most TTC8 mutations are loss-of-function (nonsense, frameshift, splice-site), leading to BBS8 or RP51.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
Not described; TTC8 disease is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
| • protein binding (GO:0005515) | • BBSome complex (GO:0034464) |
| • cilium assembly (GO:0060271) | • intraciliary transport involved in cilium assembly (GO:0035735) |
Pathways
• BBSome-mediated ciliary trafficking (Reactome: R-HSA-5620912)
• Ciliopathy pathway (KEGG: hsa05016)
Protein Summary
The TTC8 protein (also known as BBS8) contains multiple tetratricopeptide repeats that mediate protein-protein interactions within the BBSome complex. It localizes to the basal body and ciliary axoneme, facilitating the transport of membrane proteins into cilia. Loss of TTC8 function disrupts ciliary signaling and leads to pleiotropic phenotypes including retinal degeneration, obesity, and renal anomalies.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| TTC8 Knockout HEK293 Cell Line | EDJ-KQ8170 | Human | 123016 | Details Get a Quote |
| TTC8 Knockout A-549 Cell Line | EDJ-KQ34080 | Human | 123016 | Details Get a Quote |
| TTC8 Knockout HCT 116 Cell Line | EDJ-KQ34081 | Human | 123016 | Details Get a Quote |
| TTC8 Knockout HeLa Cell Line | EDJ-KQ34082 | Human | 123016 | Details Get a Quote |
Displaying Records 1 To 4 Of 4 Records
