bio-atac-seq-motif-deviation

bio-atac-seq-motif-deviation is a skill for Claude Code, Codex from GPTomics/bioSkills. It costs 70 tokens per session (5,079 once invoked), scanned A, original, MIT.

A workflow for measuring how much the accessibility of DNA motifs varies across samples or individual cells. A motif is a short DNA pattern that can be recognized by a transcription factor.

In plain words
What is it for?
Use it to rank transcription-factor motifs associated with accessibility differences, compare samples or cells, and analyze motif variation with chromVAR, ArchR, or Signac.
Why use it?
Raw motif matches do not show whether those sites are more or less accessible in a sample. This workflow calculates background-corrected scores while accounting for factors such as GC content and overall accessibility.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/gptomics/bioskills/motif-deviation
Any agent
npx skills add GPTomics/bioSkills --skill motif-deviation
Clone the repo
git clone --depth 1 https://github.com/GPTomics/bioSkills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for bio-atac-seq-motif-deviation

README.md
[![agentmods](https://agentmods.dev/badge/skills/gptomics/bioskills/motif-deviation.svg)](https://agentmods.dev/skills/gptomics/bioskills/motif-deviation)
Your own site
<a href="https://agentmods.dev/skills/gptomics/bioskills/motif-deviation"><img src="https://agentmods.dev/badge/skills/gptomics/bioskills/motif-deviation.svg" alt="Measured on agentmods" height="20"></a>
Per session 70 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,079 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00070 $0.05079
Opus 5 $0.00035 $0.02540
Sonnet 5 $0.00014 $0.01016
Haiku 4.5 $0.00007 $0.00508

Measured 6d ago against content hash de292fdd7cfc, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

bio-atac-seq-motif-deviation scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

atac-seq/motif-deviation/SKILL.md · 333 lines

How it starts

The opening of the file, as written. The whole thing — 333 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Version Compatibility

Reference examples tested with: chromVAR 1.24+, motifmatchr 1.24+, JASPAR2024 0.99+, TFBSTools 1.40+, BSgenome.Hsapiens.UCSC.hg38 1.4+, SummarizedExperiment 1.32+, limma 3.58+, ggplot2 3.5+, Matrix 1.6+, ArchR 1.0.2+, Signac 1.13+.

Before using code patterns, verify installed versions match. If versions differ:

  • R: packageVersion('<pkg>') then ?function_name to verify parameters

If code throws unexpected errors, introspect the installed package and adapt rather than retrying.

Motif Deviation (chromVAR)

"Which TF motifs explain accessibility variation across my samples or cells?" -> Compute per-sample (or per-cell) deviation z-scores: how many standard deviations above expectation each TF motif's accessibility falls, controlling for GC content and overall accessibility via matched background peak sets.

  • R: chromVAR::computeDeviations(counts, motifs) -> per-sample z-scores
  • R: chromVAR::computeVariability(dev) -> per-motif variance ranking
  • Single-cell alternative: Signac::RunChromVAR() (wrapper with matched defaults) or ArchR::addDeviationsMatrix()

chromVAR answers a different question than footprinting: footprinting asks "is this specific motif site bound?", chromVAR asks "do peaks containing this motif have systematically more or less accessibility than expected?" The two are complementary.

What chromVAR Computes

For each (motif, sample) pair:

  • Raw deviation = Sum of accessibility at peaks containing the motif - expected from a matched-GC, matched-accessibility background.
  • Bias-corrected deviation = Raw deviation / SD of background deviations.
  • Z-score = (corrected deviation - mean across cells) / SD across cells. Reported as the principal output.

Z-scores are signed: positive = motif more accessible in this sample than population average; negative = less. Magnitudes 2-5 are typical for biologically interesting motifs; >5 indicates strong covariation with sample state.

Algorithmic Taxonomy

Read the full file on GitHub · 333 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 333 lines · 70 tokens per session scan A de292fdd7cfc

Subscribe to this mod's changes

bio-atac-seq-motif-deviation is a skill published in the GitHub repository GPTomics/bioSkills (1,199 stars, last pushed 21d ago), licensed MIT. It adds 70 tokens to every session and 5,079 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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