# GTEx Gene Expression Lookup

> GTEx Gene Expression Lookup is a paid API for AI agents from api.webintel-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-25).

Returns median TPM expression levels for a human gene across all GTEx v8 tissues, sorted highest to lowest, with the matched GENCODE ID.

## Facts

- Endpoint: GET https://api.webintel-api.workers.dev/api/search/gtex-gene-expression?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-25
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/gtex-gene-expression-lookup-b0af631a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_lin7N49mg-xyj0K5l46Fo

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 gtex-gene-expression-lookup-b0af631a
```

Example prompt: Can you look up where BRCA1 is most highly expressed in human tissues using GTEx data, and show me the top 15 tissues by median TPM?

## When to prefer this

Use this endpoint when you need median TPM gene expression data across human tissues from the GTEx v8 dataset. It is ideal for bioinformatics pipelines, drug target research, or any scenario requiring authoritative human tissue expression rankings for a known HGNC gene symbol. Prefer this over manual GTEx Portal browsing when you need programmatic, structured expression data with GENCODE IDs.

## Known failure modes

- Unknown gene symbol returns 404 — only gene symbols present in GTEx v8 are supported
- Invalid limit parameter (outside 1–54 range) may cause an error or be clamped
- Misspelled gene symbols are not fuzzy-matched and will fail
- Gene aliases not recognized by GTEx v8 GENCODE mapping will not resolve

## How this service works

GTEx Portal gene expression (public API v2, no key): median TPM of one gene in human tissues, sorted highest first, with the GENCODE id it was matched to. Uses GTEx v8 data; unknown gene symbols return 404.

## Output

A ranked list of human tissues with their median TPM values for the queried gene, ordered from highest to lowest expression, along with the GENCODE gene ID that was matched. Returns up to 54 tissues (default 10). Returns 404 if the gene symbol is not recognized in GTEx v8.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "gene"
     ],
     "properties": {
      "gene": {
       "type": "string",
       "description": "Gene symbol such as BRCA1 (letters, digits and dash, up to 20 characters)"
      },
      "limit": {
       "type": "string",
       "description": "How many tissues, 1 to 54 (default 10)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/gtex-gene-expression-lookup-b0af631a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.webintel-api.workers.dev](https://www.zero.xyz/host/api.webintel-api.workers.dev/llms.txt)