---
title: "Get variants for a single gene (on-demand)"
method: GET
path: "/sessions/{session_id}/variants/by-gene/{gene_symbol}"
tags: ["variants-streaming"]
---

# Get variants for a single gene (on-demand)

`GET /sessions/{session_id}/variants/by-gene/{gene_symbol}`

## Request

- Base URL: `https://api.helena.bio` (the document declares no server; this is the origin it was published from)
- URL: `https://api.helena.bio/sessions/{session_id}/variants/by-gene/{gene_symbol}`
- Auth: none declared

Fetch all variants for a specific gene from DuckDB. Used for lazy gene expansion.

## Path parameters

- `session_id` string, uuid, required
- `gene_symbol` string, required

## Query parameters

- `expected_version` string, nullable

## Response `200`

Successful Response

- unknown

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/helena/apis/helix-insight-variant-analysis-service.md) · [All operations](https://skmtc.dev/helena/apis/helix-insight-variant-analysis-service/llms.txt) · [OpenAPI document](https://skmtc.dev/helena/apis/helix-insight-variant-analysis-service/revisions/fe51fd20cdf1?raw)