# Gene Expression Lookup by Tissue (GTEx)

> Gene Expression Lookup by Tissue (GTEx) is a paid API for AI agents from win.oneshotagent.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-25).

Returns median TPM expression of a human gene across normal tissues, ranked highest to lowest, using GTEx v11 data.

## Facts

- Endpoint: POST https://win.oneshotagent.com/v1/tools/lookup/gene-expression?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-25
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/gene-expression-lookup-by-tissue-gtex-7438fae6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_kuQKvuMtsGbRpHJadq_UX

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability gene-expression-lookup-by-tissue-gtex-7438fae6 -d '<json body>'
```

Example prompt: What are the top 5 tissues where TP53 is most expressed in normal human tissue? Use the GTEx dataset and show me the median TPM values.

## When to prefer this

Use this endpoint when you need authoritative, curated median expression data for a human gene across normal (non-diseased) tissues from the GTEx v11 dataset. Prefer this over RNA-seq database queries or literature lookups when you need structured, machine-readable TPM values ranked by expression level. Ideal for drug target assessment, biomarker validation, tissue specificity analysis, or any pipeline that needs normalized expression baselines.

## Known failure modes

- Unrecognized gene symbol or Ensembl ID returns matched:false with empty tissues array
- Invalid characters in gene name return a validation error
- Limit out of range (>60 or <1) returns a schema validation error
- Network timeout for very broad queries
- Gene exists but has no GTEx data (e.g. very new genes not in v11)

## How this service works

Look up median expression of a human gene across normal tissues, highest expression first.

## Output

Returns a JSON object containing gene metadata (symbol, chromosome, Ensembl ID, Entrez ID, description), the unit (TPM), dataset version (gtex_v11), and an ordered array of tissues with their median TPM values and ontology IDs, sorted highest expression first.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "gene": {
   "type": "string",
   "description": "Official human gene symbol (TP53) or Ensembl gene ID (ENSG00000141510), with or without a version. 1 to 30 characters. Letters, digits, \".\", \"_\" and \"-\" only."
  },
  "limit": {
   "type": "integer",
   "description": "Tissues returned, highest median first; omit for all tissues. From 1 to 60."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "gene": {
   "symbol": "TP53",
   "chromosome": "chr17",
   "ensembl_id": "ENSG00000141510",
   "gencode_id": "ENSG00000141510.19",
   "description": "tumor protein p53",
   "entrez_gene_id": 7157
  },
  "unit": "TPM",
  "dataset": "gtex_v11",
  "matched": true,
  "tissues": [
   {
    "tissue": "Cells_EBV-transformed_lymphocytes",
    "median_tpm": 54.4686,
    "ontology_id": "EFO:0000572"
   },
   {
    "tissue": "Skin_Sun_Exposed_Lower_leg",
    "median_tpm": 25.8191,
    "ontology_id": "UBERON:8480050"
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/gene-expression-lookup-by-tissue-gtex-7438fae6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from win.oneshotagent.com](https://www.zero.xyz/host/win.oneshotagent.com/llms.txt)