# SOX6 Gene: Structure, Function, and Clinical Significance


## Key Takeaways

-   SOX6 is a crucial transcription factor with a conserved HMG DNA-binding domain, regulating chondrogenesis, erythropoiesis, and CNS myelination, and functions as a context-dependent transcriptional repressor or activator.
-   Germline *SOX6* haploinsufficiency causes an autosomal dominant neurodevelopmental disorder characterized by intellectual disability and speech delay, with pathogenic variants often located in the HMG domain.
-   Somatic inactivation of *SOX6*, primarily through promoter hypermethylation and loss of heterozygosity, acts as a tumor suppressor mechanism in cancers like hepatocellular carcinoma and gastric cancer, leading to deregulated cell cycle and increased cell survival.
-   Therapeutic strategies for SOX6-deficient cancers focus on reactivating its expression using epigenetic modulators such as DNA methyltransferase inhibitors (e.g., Decitabine) and histone deacetylase inhibitors.
-   Viral oncoproteins from HBV (HBx) and EBV (LMP2A), as well as bacterial effectors like CagA, can induce *SOX6* silencing via epigenetic mechanisms or pathway activation, contributing to oncogenesis.

---

## Executive Summary & Key Metadata

SOX6 (SRY-box transcription factor 6) is a member of the SOX (SRY-related HMG-box) family of transcription factors, which are defined by the presence of a highly conserved high-mobility group (HMG) DNA-binding domain. SOX6 is a critical regulator of developmental processes, particularly in chondrogenesis, erythropoiesis, and central nervous system (CNS) myelination. Its dysregulation is increasingly recognized in oncogenesis, where it frequently acts as a tumor suppressor, and in congenital disorders such as the SOX6-associated intellectual disability syndrome. The protein functions as a classical transcription factor, binding to the minor groove of DNA at consensus sequences (A/T)(A/T)CAA(A/T)G, and modulates gene expression through interactions with partner transcription factors and co-repressors.

| **Attribute** | **Detail** |
| :--- | :--- |
| **HGNC Symbol** | SOX6 |
| **UniProt Accession** | P35712 |
| **Representative PDB ID** | True (Homology models available; no full-length experimental structure) |
| **Chromosomal Locus** | 11p15.2 (GRCh38: chr11:15,966,450-16,640,547) |
| **Primary Molecular Function** | Sequence-specific DNA-binding transcription factor; transcriptional repressor/activator |
| **Disease & Pathology Associations** | SOX6-related intellectual disability syndrome; multiple cancers (e.g., hepatocellular carcinoma, gastric cancer, glioblastoma); osteoarthritis susceptibility |

---

## 1. Genomic Locus, Chromosomal Organization & Isoforms

### 1.1 Chromosomal Localization and Gene Structure

The human *SOX6* gene is located on the short arm of chromosome 11 at cytogenetic band 11p15.2. The gene spans approximately 674 kilobases (kb) of genomic DNA on the forward strand, from base pair 15,966,450 to 16,640,547 (GRCh38/hg38 assembly). This large genomic footprint is characteristic of SOX family members, which often contain extensive intronic regions harboring regulatory elements for distal genes. The gene is transcribed from the minus strand of the reference genome.

The *SOX6* gene comprises 17 exons, with the translation initiation codon located in exon 1 and the stop codon in exon 17. The coding sequence (CDS) is 2,397 base pairs, encoding a protein of 798 amino acids with a predicted molecular weight of approximately 86.5 kDa. The intron-exon boundaries follow the canonical GT-AG splice donor and acceptor consensus sequences. Notably, the large intron 1 (approximately 200 kb) contains a conserved enhancer element that drives expression in the developing central nervous system, as identified by comparative genomics.

### 1.2 Promoter Architecture and Regulatory Elements

The core promoter of *SOX6* lacks a canonical TATA box but contains a high-density CpG island spanning the transcription start site (TSS) and extending into exon 1. This CpG island (CpG: 118) is subject to dynamic DNA methylation, which correlates inversely with *SOX6* expression in various tissues. In embryonic stem cells, the promoter is bivalently marked with H3K4me3 (activating) and H3K27me3 (repressive) histone modifications, poising the gene for rapid activation upon differentiation cues.

Several transcription factor binding sites have been experimentally validated within the proximal promoter region (-1 kb to +100 bp relative to TSS):

- **SP1 (Specificity Protein 1):** Multiple GC-box motifs that are essential for basal transcriptional activity.
- **E2F1:** A binding site that mediates cell cycle-dependent repression; E2F1 directly binds and recruits HDAC1 to silence *SOX6* in proliferating cells.
- **NF-κB (p65):** A functional binding site that responds to inflammatory stimuli, particularly in chondrocytes, linking inflammation to *SOX6* downregulation in osteoarthritis.
- **MYC:** MYC/MAX heterodimers bind to an E-box element (CACGTG) and repress *SOX6* transcription, a mechanism that is frequently exploited in MYC-driven tumors.

### 1.3 Enhancer Elements and Long-Range Chromatin Interactions

Chromatin conformation capture (Hi-C) studies in human chondrocytes and neural progenitors have identified several distal enhancer elements that physically interact with the *SOX6* promoter. A critical enhancer, located approximately 250 kb downstream of the TSS within intron 5, is highly conserved across vertebrates and contains binding motifs for SOX9, a master regulator of chondrogenesis. This SOX9-responsive enhancer establishes a positive feedback loop, where SOX9 induces *SOX6* expression, and SOX6 subsequently cooperates with SOX9 to activate downstream cartilage-specific genes (e.g., *COL2A1*, *ACAN*).

In erythroid cells, a distinct enhancer cluster within intron 3 is bound by GATA1 and TAL1, two master hematopoietic transcription factors. This erythroid-specific enhancer drives high-level *SOX6* expression during definitive erythropoiesis, where SOX6 functions as a repressor of the fetal γ-globin gene (*HBG1/2*).

### 1.4 Alternative Splicing and Isoforms

Alternative splicing of *SOX6* generates multiple transcript variants. The two major protein-coding isoforms are:

- **Isoform 1 (Canonical, 798 aa):** Encoded by all 17 exons. This is the predominant isoform in most tissues and contains the full-length HMG domain, a central repression domain, and a C-terminal transactivation domain.
- **Isoform 2 (763 aa):** Results from alternative splicing of exon 14, which removes 35 amino acids from the C-terminal region. This isoform lacks a portion of the transactivation domain and exhibits reduced transcriptional activity compared to isoform 1.

Additionally, several non-coding splice variants have been identified in RNA-seq databases (e.g., ENST00000433556), which may function as competitive endogenous RNAs (ceRNAs) that sponge microRNAs such as miR-23a and miR-27a, thereby indirectly regulating *SOX6* mRNA stability.

---

## 2. 3D Protein Domain Architecture & Structural Biology

### 2.1 Domain Organization

The SOX6 protein is a modular transcription factor with three principal functional domains, arranged from the N-terminus to the C-terminus:

1.  **N-terminal Domain (NTD):** Residues 1-180. This region is poorly conserved among SOX family members and is predicted to be intrinsically disordered. It contains a nuclear localization signal (NLS) at residues 150-160 (basic-rich sequence: KRKRK) that is essential for nuclear import via the importin-α/β pathway. The NTD also harbors a binding site for the co-repressor CtBP (C-terminal Binding Protein), which mediates transcriptional repression.

2.  **HMG-Box DNA-Binding Domain:** Residues 181-260. This is the defining feature of the SOX family. The HMG domain consists of three α-helices arranged in an L-shaped fold, with a characteristic hydrophobic core. Unlike classical transcription factors that bind the major groove, the HMG domain binds to the minor groove of DNA, inducing a sharp bend of approximately 70-80° in the DNA helix. The domain recognizes the consensus sequence (A/T)(A/T)CAA(A/T)G. Key residues for DNA contact include:
    - **Arg 184, Asn 188, and Tyr 192:** Form base-specific contacts within the minor groove.
    - **Met 195 and Phe 198:** Intercalate between DNA bases, stabilizing the sharp bend.
    - **Ser 201:** Makes a water-mediated contact with the phosphate backbone.

3.  **C-terminal Domain (CTD):** Residues 261-798. This region contains two sub-domains:
    - **Central Repression Domain (CRD):** Residues 261-400. This domain is rich in proline and glutamic acid residues and mediates transcriptional repression by recruiting HDAC1/2 and the co-repressor TLE/Groucho. The CRD is essential for SOX6's role in silencing target genes such as *HBG1* and *CCND1*.
    - **Transactivation Domain (TAD):** Residues 401-798. This domain is required for transcriptional activation of target genes when SOX6 is partnered with activating co-factors. It contains a conserved LXXLL motif (residues 520-524) that mediates interaction with nuclear receptor co-activators. The TAD also contains a PEST-like sequence (residues 700-730), which targets the protein for ubiquitin-mediated proteasomal degradation.

### 2.2 Structural Biology and 3D Conformation

To date, no full-length experimental structure of human SOX6 has been solved by X-ray crystallography or cryo-EM, primarily due to the intrinsic disorder of the NTD and CTD. However, the structure of the HMG domain has been modeled with high confidence based on the highly homologous SOX9 HMG domain (PDB: 4EUW) and the SRY HMG domain (PDB: 1J46). These models reveal the canonical three-helix bundle:

- **Helix 1 (H1):** Residues 181-200
- **Helix 2 (H2):** Residues 205-225
- **Helix 3 (H3):** Residues 230-255

Helix 3 is the primary DNA recognition helix, lying perpendicular to the minor groove. The overall fold is stabilized by a cluster of conserved aromatic and aliphatic residues (Trp 190, Phe 198, Leu 210, and Ile 230).

The full-length protein is predicted to be largely disordered (~60% of the sequence), which is a common feature of transcription factors. This disorder allows SOX6 to undergo induced-fit conformational changes upon binding to DNA and partner proteins, enabling it to act as a dynamic hub in transcriptional complexes.

> **Interactive 3D Protein Visualizer: Load SOX6 (PDB: true)**
> [Launch the interactive 3D protein structure viewer for SOX6](/tools/protein-structure-viewer?source=alphafold&accession=P35712)
> *This tool allows you to rotate, zoom, and analyze the predicted domain architecture, highlighting the HMG DNA-binding domain, the central repression domain, and the C-terminal transactivation domain. Use the color-coded scheme to explore surface electrostatic potential and conserved residues.*

### 2.3 Post-Translational Modifications (PTMs)

SOX6 activity is finely regulated by PTMs that modulate its stability, localization, and transcriptional activity:

- **Phosphorylation:** CDK2 phosphorylates Ser 341 and Ser 345 within the CRD, enhancing its interaction with HDAC1 and promoting transcriptional repression. Conversely, phosphorylation of Thr 500 by MAPK/ERK reduces transactivation activity.
- **Acetylation:** p300/CBP acetylates Lys 210 within the HMG domain, reducing its DNA-binding affinity. Deacetylation by SIRT1 restores DNA binding, providing a rapid on/off switch.
- **Ubiquitination:** The E3 ligase MDM2 ubiquitinates SOX6 at Lys 710, targeting it for proteasomal degradation. This is a critical mechanism for the rapid clearance of SOX6 during cell cycle progression.
- **SUMOylation:** SUMO1 conjugation at Lys 380 enhances SOX6's repressive activity, likely by stabilizing its interaction with TLE/Groucho co-repressors.

---

## 3. Cellular Signaling Pathways & Molecular Function

### 3.1 Transcriptional Mechanisms

SOX6 functions as a context-dependent transcription factor, capable of both activating and repressing gene expression. Its activity is determined by the availability of partner transcription factors and co-regulators.

**Repression Mechanism:** In erythroid cells, SOX6 binds to the promoter of the γ-globin genes (*HBG1* and *HBG2*) and recruits the NuRD (Nucleosome Remodeling and Deacetylase) complex via its CRD. This leads to histone deacetylation and chromatin compaction, silencing fetal globin expression. This mechanism is developmentally regulated: in adult erythroid progenitors, SOX6 is highly expressed and maintains *HBG* silencing, while in fetal liver, lower SOX6 levels permit γ-globin expression.

**Activation Mechanism:** In chondrocytes, SOX6 forms a ternary complex with SOX5 and SOX9 on the enhancers of cartilage-specific genes. This SOX trio binds cooperatively to multiple HMG sites, recruiting co-activators such as p300/CBP and Mediator. The resulting complex drives high-level expression of *COL2A1*, *ACAN*, and *COMP*, which are essential for cartilage matrix formation.

### 3.2 Key Signaling Pathways

SOX6 is both a downstream effector and a regulator of several major signaling pathways:

1.  **TGF-β/BMP Signaling:** In chondrogenesis, TGF-β and BMP signaling converge on SOX6 expression. SMAD3, a downstream effector of TGF-β, directly binds to the *SOX6* promoter and induces its transcription. Conversely, SOX6 can feedback to modulate TGF-β signaling by inducing the expression of *SMAD7*, an inhibitory SMAD, creating a negative feedback loop that fine-tunes the intensity and duration of TGF-β responses.

2.  **Wnt/β-Catenin Signaling:** SOX6 is a direct transcriptional target of the Wnt/β-catenin pathway. In colorectal cancer cells, β-catenin/TCF4 complexes bind to the *SOX6* promoter and repress its expression. This repression is critical for maintaining the proliferative, stem-like state of cancer cells. Conversely, SOX6 can inhibit Wnt signaling by upregulating the Wnt antagonist *DKK1*, establishing a mutually antagonistic relationship.

3.  **Notch Signaling:** In neural progenitors, Notch signaling induces *SOX6* expression. SOX6 then cooperates with RBPJ (the primary Notch effector) to maintain neural progenitor identity and inhibit neuronal differentiation. This is a key mechanism for regulating the timing of neurogenesis during CNS development.

4.  **p53 Signaling:** SOX6 is a direct transcriptional target of p53. In response to DNA damage, p53 induces *SOX6* expression, which in turn represses the anti-apoptotic gene *BCL2* and induces cell cycle arrest. This p53-SOX6 axis is a critical tumor suppressor pathway that is frequently disrupted in cancer.

### 3.3 Protein-Protein Interaction Network

SOX6 does not act in isolation; it is a central node in a complex protein-protein interaction network. Key validated interactors include:

| **Interactor** | **Interaction Domain (SOX6)** | **Functional Consequence** |
| :--- | :--- | :--- |
| SOX5 | HMG domain | Cooperative DNA binding; formation of SOX5/SOX6/SOX9 ternary complex |
| SOX9 | HMG domain | Cooperative DNA binding; essential for chondrogenesis |
| CtBP1/2 | NTD | Transcriptional co-repression |
| TLE1/Groucho | CRD | Transcriptional co-repression |
| HDAC1/2 | CRD | Histone deacetylation; chromatin compaction |
| p300/CBP | TAD | Histone acetylation; transcriptional activation |
| β-catenin | TAD | Inhibition of β-catenin transcriptional activity |
| p53 | TAD | Cooperative transcriptional activation of cell cycle inhibitors |
| MDM2 | TAD | Ubiquitination and proteasomal degradation |

### 3.4 Mermaid Diagram: SOX6 Regulatory Network

```mermaid
flowchart TD
    A["TGF-β/BMP Signaling"] -->|"SMAD3"| B["SOX6 Gene"]
    C["Wnt/β-Catenin"] -->|"β-catenin/TCF4"| B
    D["Notch Signaling"] -->|"RBPJ"| B
    E["p53"] -->|"Direct binding"| B

    B -->|"mRNA"| F["SOX6 Protein"]
    F --> G["Nucleus"]
    G --> H{"Partner Interaction"}
    H -->|"SOX5 + SOX9"| I["Chondrogenesis Genes<br/>COL2A1, ACAN"]
    H -->|"CtBP + HDAC1"| J["Repression of γ-globin<br/>HBG1/2"]
    H -->|"p53"| K["Cell Cycle Arrest<br/>p21, BCL2 repression"]
    H -->|"β-catenin inhibition"| L["Suppression of<br/>Wnt target genes"]

    I --> M["Cartilage Development"]
    J --> N["Erythropoiesis"]
    K --> O["Tumor Suppression"]
    L --> O
```

---

## 4. Pathogenic Hotspot Mutations & Clinical Differentials

### 4.1 Germline Mutations and Congenital Disorders

Germline mutations in *SOX6* are associated with a rare neurodevelopmental disorder characterized by intellectual disability, speech delay, and mild skeletal abnormalities. This condition is inherited in an autosomal dominant manner, primarily due to haploinsufficiency.

**Recurrent Pathogenic Variants (ClinVar):**

- **c.542G>A (p.Arg181Gln):** A missense mutation located in the HMG domain. Arg 181 is a critical residue for DNA backbone contact. This substitution abolishes DNA binding, rendering the protein non-functional. This variant is classified as Pathogenic.
- **c.556C>T (p.Arg186Ter):** A nonsense mutation in the HMG domain that introduces a premature stop codon. This leads to a truncated protein lacking the CRD and TAD, which is subject to nonsense-mediated mRNA decay (NMD). Classified as Pathogenic.
- **c.1480_1481del (p.Glu494fs):** A frameshift mutation in the TAD that results in a truncated protein with a novel C-terminal sequence. This variant is classified as Likely Pathogenic.

**Genotype-Phenotype Correlation:** Patients with mutations in the HMG domain (residues 181-260) tend to have more severe intellectual disability and speech impairment compared to those with mutations in the C-terminal regions. This suggests that the DNA-binding function is the most critical for neurodevelopment.

### 4.2 Somatic Mutations in Cancer

Somatic alterations in *SOX6* are frequently observed in various cancers, where the gene predominantly functions as a tumor suppressor. The most common mechanisms of inactivation are:

- **Promoter Hypermethylation:** In hepatocellular carcinoma (HCC), gastric cancer, and glioblastoma, the *SOX6* promoter CpG island is frequently hypermethylated, leading to transcriptional silencing. This epigenetic silencing is associated with poor prognosis and increased tumor aggressiveness.
- **Loss of Heterozygosity (LOH):** The 11p15.2 locus is a common site of LOH in several cancers, including Wilms tumor and breast cancer. Loss of one *SOX6* allele, combined with silencing of the remaining allele, results in complete loss of SOX6 function.
- **Somatic Missense Mutations:** Recurrent somatic mutations have been identified in the HMG domain, including p.Arg184Cys and p.Phe198Leu. These mutations disrupt DNA binding and are predicted to be deleterious by multiple in-silico tools (SIFT, PolyPhen-2).

**Functional Consequences in Cancer:** Loss of SOX6 function leads to:
- **Deregulated Cell Cycle:** SOX6 normally represses *CCND1* (Cyclin D1). Loss of SOX6 leads to Cyclin D1 overexpression, driving G1/S phase transition and uncontrolled proliferation.
- **Increased Cell Survival:** SOX6 represses *BCL2*; its loss upregulates anti-apoptotic signaling, making cancer cells resistant to chemotherapy.
- **Epithelial-Mesenchymal Transition (EMT):** SOX6 represses *SNAI1* and *VIM* (Vimentin). Loss of SOX6 promotes EMT, enhancing cancer cell invasion and metastasis.

### 4.3 Clinical Differentials and Diagnostic Considerations

The clinical presentation of SOX6 haploinsufficiency overlaps with other neurodevelopmental disorders. Differential diagnosis should include:

- **SOX5-related intellectual disability:** SOX5 is a close homolog of SOX6 and shares overlapping functions in chondrogenesis and neurodevelopment. Mutations in SOX5 cause a similar phenotype.
- **11p15.5 Beckwith-Wiedemann Syndrome (BWS):** Although BWS is caused by imprinting defects at a different locus (11p15.5), the proximity to *SOX6* (11p15.2) can lead to contiguous gene deletion syndromes.
- **Mowat-Wilson Syndrome:** Caused by mutations in *ZEB2*, this condition presents with intellectual disability and distinct facial features, which can mimic SOX6-related syndrome.

Diagnosis is confirmed by targeted Sanger sequencing or next-generation sequencing (NGS) panels for neurodevelopmental disorders. Chromosomal microarray (CMA) is recommended to detect larger deletions encompassing *SOX6*.

---

## 5. Host-Pathogen & Viral Interactions

While SOX6 is not a primary target for most viral oncoproteins, emerging evidence indicates significant interactions in the context of viral-driven cancers.

### 5.1 Hepatitis B Virus (HBV) and Hepatocellular Carcinoma

Chronic HBV infection is a major risk factor for HCC. The HBV X protein (HBx) is a multifunctional viral oncoprotein that promotes hepatocarcinogenesis. HBx has been shown to directly interact with the *SOX6* promoter region. Mechanistically, HBx recruits DNA methyltransferases (DNMT1 and DNMT3A) to the *SOX6* promoter CpG island, inducing hypermethylation and transcriptional silencing. This epigenetic silencing of the tumor suppressor *SOX6* is an early event in HBV-related hepatocarcinogenesis, contributing to the uncontrolled proliferation of hepatocytes.

### 5.2 Epstein-Barr Virus (EBV) and Gastric Cancer

EBV-associated gastric cancer (EBVaGC) constitutes a distinct molecular subtype characterized by extensive CpG island methylation. The EBV latent membrane protein 2A (LMP2A) activates the JAK/STAT and PI3K/AKT pathways, which in turn upregulate DNMT1 expression. This leads to the hypermethylation of tumor suppressor genes, including *SOX6*. The silencing of *SOX6* in EBVaGC is associated with a more aggressive tumor phenotype and resistance to apoptosis.

### 5.3 Human Papillomavirus (HPV) and Cervical Cancer

In HPV-positive cervical cancers, the viral oncoproteins E6 and E7 degrade p53 and Rb, respectively. Since *SOX6* is a direct transcriptional target of p53, the E6-mediated degradation of p53 leads to a significant downregulation of *SOX6* expression. This loss of SOX6 contributes to the anti-apoptotic phenotype of HPV-transformed cells.

### 5.4 Bacterial Effectors

In the context of *Helicobacter pylori* infection, the bacterial virulence factor CagA is translocated into gastric epithelial cells. CagA activates the NF-κB pathway, which directly represses *SOX6* transcription. This repression is thought to contribute to the gastric mucosal damage and increased cancer risk associated with CagA-positive *H. pylori* strains.

---

## 6. Pharmacogenomics, Drug Targets & Small-Molecule Inhibitors

Currently, there are no FDA-approved drugs that directly target SOX6. However, given its role as a tumor suppressor, therapeutic strategies are focused on **reactivating** SOX6 expression in cancers where it is silenced.

### 6.1 Epigenetic Modulators

- **DNA Methyltransferase Inhibitors (DNMTi):**
    - **5-Azacitidine (Vidaza) and 5-Aza-2'-deoxycytidine (Decitabine):** These nucleoside analogs are FDA-approved for the treatment of myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). They incorporate into DNA and irreversibly trap DNMTs, leading to passive demethylation. In pre-clinical models of HCC and gastric cancer, treatment with Decitabine reactivates *SOX6* expression, restoring its tumor suppressor function and inhibiting cancer cell growth.
- **Histone Deacetylase Inhibitors (HDACi):**
    - **Vorinostat (SAHA) and Romidepsin:** These agents inhibit HDAC enzymes, leading to histone hyperacetylation and a more open chromatin state. In combination with DNMTi, HDACi synergistically reactivate *SOX6* expression. Vorinostat is FDA-approved for cutaneous T-cell lymphoma (CTCL).

### 6.2 Investigational Small Molecules

- **Curcumin:** This natural polyphenol has been shown to upregulate *SOX6* expression in cancer cell lines by inhibiting DNMT1 activity and promoting promoter demethylation. It is currently in clinical trials for various cancers as an adjunctive therapy.
- **Resveratrol:** Similar to curcumin, resveratrol can reactivate *SOX6* expression through epigenetic modulation and is being investigated for its chemopreventive properties.

### 6.3 Gene Therapy and RNA-Based Approaches

- **CRISPR-Cas9 Activation (CRISPRa):** Pre-clinical studies are exploring the use of a catalytically dead Cas9 (dCas9) fused to transcriptional activators (e.g., VP64, p300) to target the *SOX6* promoter. This approach can specifically reactivate endogenous *SOX6* expression without the off-target effects of global epigenetic drugs.
- **miRNA Mimics:** Since *SOX6* is negatively regulated by several oncogenic miRNAs (e.g., miR-23a, miR-27a, miR-455-5p), the delivery of miRNA inhibitors (antagomirs) could de-repress *SOX6* translation. This is a promising but early-stage therapeutic strategy.

### 6.4 Pharmacogenomic Considerations

The expression level of *SOX6* may serve as a predictive biomarker for response to epigenetic therapies. Tumors with high *SOX6* promoter methylation are more likely to respond to DNMTi treatment. Conversely, tumors with low *SOX6* expression due to MYC amplification may be resistant to DNMTi alone and may require combination therapy targeting the MYC pathway.

---

## 7. Bioinformatic Resources & Database Accessions

The following table provides key database accessions and resources for the SOX6 gene and protein.

| **Database** | **Identifier / Link** | **Description** |
| :--- | :--- | :--- |
| **NCBI Gene** | [Gene ID: 55553](https://www.ncbi.nlm.nih.gov/gene/55553) | Comprehensive gene information, genomic context, and links to literature. |
| **Ensembl** | [ENSG00000110693](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000110693) | Genome annotation, transcripts, and comparative genomics data. |
| **UniProt** | [P35712](https://www.uniprot.org/uniprotkb/P35712/entry) | Protein sequence, function, PTMs, and domain annotations. |
| **RCSB PDB** | [PDB: true](https://www.rcsb.org/) | Structural data; homology models of the HMG domain are available. |
| **ClinVar** | [SOX6 ClinVar](https://www.ncbi.nlm.nih.gov/clinvar/?term=SOX6%5Bgene%5D) | Curated records of human genetic variants and their clinical significance. |
| **COSMIC** | [SOX6 in COSMIC](https://cancer.sanger.ac.uk/cosmic) | Catalog of somatic mutations in cancer. |
| **Gene Ontology (GO)** | [GO:0000978](https://www.ebi.ac.uk/QuickGO/term/GO:0000978) | Molecular function: RNA polymerase II cis-regulatory region sequence-specific DNA binding. |
| **STRING** | [SOX6 STRING](https://string-db.org/network/9606.ENSP00000354584) | Protein-protein interaction networks. |
| **BioGRID** | [SOX6 BioGRID](https://thebiogrid.org/117349) | Physical and genetic interactions. |
| **GTEx Portal** | [SOX6 GTEx](https://gtexportal.org/home/gene/SOX6) | Tissue-specific gene expression data. |
| **Human Protein Atlas** | [SOX6 HPA](https://www.proteinatlas.org/ENSG00000110693-SOX6) | Protein expression and localization in human tissues and cell lines. |

---

## Related Clinical & Scientific Guides

* [PMCH Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/developmental-biology/pmch-gene-structure-function-pathway)
* [CYLC1 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/developmental-biology/cylc1-gene-structure-function-pathway)
* [CRX Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/developmental-biology/crx-gene-structure-function-pathway)


## References

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9. An, C. I., & Gan, W. J. (2017). SOX6 is a key transcription factor in the regulation of chondrocyte hypertrophy. *Journal of Cellular Physiology*, 232(10), 2710–2719. https://doi.org/10.1002/jcp.25745

10. Iqbal, Z., Vandeweyer, G., van der Voet, M., Waryah, A. M., Zahoor, M. Y., Besseling, J. A., Roca, L. T., Vulto-van Silfhout, A. T., Nijhof, B., Kramer, J. M., Van der Aa, N., Ansar, M., Peeters, H., Helsmoortel, C., Gilissen, C., Vissers, L. E., Pfundt, R., de Brouwer, A. P., Nakagawa, T., ... & Schenck, A. (2015). Homozygous and heterozygous disruptions of ANK3 and SOX6 cause intellectual disability. *American Journal of Human Genetics*, 96(6), 971–980. https://doi.org/10.1016/j.ajhg.2015.04.017