dna-methylation-differential-analysis

dna-methylation-differential-analysis is a skill for Claude Code, Codex from HolobiomicsLab/asb-skill-collections. It costs 54 tokens per session (2,177 once invoked), scanned A, original, Apache-2.0.

A statistical analysis step for finding DNA locations or regions where methylation differs between treatment groups. It uses bisulfite-sequencing data from at least two biological samples per group.

In plain words
What is it for?
Use it to compare methylation between conditions and classify locations as more methylated or less methylated.
Why use it?
It helps separate meaningful methylation differences from variation between samples, while filtering results by statistical confidence and effect size.

Skill for Claude CodeCodex

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

Good fit Use it to compare methylation between conditions and classify locations as more methylated or less methylated.

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Install with agentmods
npx agentmods add skills/holobiomicslab/asb-skill-collections/dna-methylation-differential-analysis
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.

Any agent
npx skills add HolobiomicsLab/asb-skill-collections --skill dna-methylation-differential-analysis
Clone the repo
git clone --depth 1 https://github.com/HolobiomicsLab/asb-skill-collections

Made for: Claude Code, Codex.

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README.md
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Your own site
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Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,177 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium analysis-evasion · line 1
    Suspicious Unicode normalization or mixed-script content
    Fix: Review the flagged content for security risks. Ensure no credentials, secrets, or sensitive data are exposed.
How audits are shown
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 $0.00054 $0.02177
Opus 5 $0.00027 $0.01089
Sonnet 5 $0.00011 $0.00435
Haiku 4.5 $0.00005 $0.00218

Measured 9d ago against content hash 53968382f9c0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

dna-methylation-differential-analysis 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 9d 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.

collections/epigenomics/v1/skills/dna-methylation-differential-analysis/SKILL.md · 107 lines

How it starts

The opening of the file, as written. The whole thing — 107 lines — stays where its author put it; the contents beside it link to each section on GitHub.

dna-methylation-differential-analysis

Summary

Identify and quantify differentially methylated bases or regions between sample groups using statistical tests that account for methylation heterogeneity and overdispersion. This skill applies Fisher's exact test or logistic regression to bisulfite sequencing methylation calls, filtered by q-value and percent methylation difference thresholds, to distinguish hyper-methylated from hypo-methylated loci.

When to use

Apply this skill when you have merged methylation call data across multiple biological replicates (samples per group ≥2) with base-pair-level coverage information, and you need to identify loci where methylation levels differ significantly between treatment groups. This is the core comparative analysis step in bisulfite sequencing workflows after quality filtering and sample merging.

When NOT to use

  • Input data lacks technical replicates or biological replication structure—statistical tests require ≥2 samples per group to estimate variance.
  • Bases have not been pre-filtered for minimum coverage (typically 10X default in methRead())—low-coverage bases produce unreliable methylation percentages.
  • You seek to analyze regional methylation (e.g., DMRs across promoters) rather than base-resolution differential calls—use regional or tiling window methods instead.

Inputs

  • methylBase object (merged sample data from unite() with base-level coverage and methylation percentages)
  • methylRawList objects (optional, for overdispersion estimation; generated by methRead() from bisulfite alignment outputs)

Outputs

  • methylDiff object containing all bases with calculated test statistics and q-values
  • hyper-methylated bases subset (type='hyper' from getMethylDiff())
  • hypo-methylated bases subset (type='hypo' from getMethylDiff())
  • numerical counts and percentages of significant bases by direction

How to apply

Execute the calculateDiffMeth() function on a methylBase object (created by merging samples with unite()) to compute differential methylation statistics. The function automatically selects Fisher's exact test for small sample sizes or logistic regression for larger cohorts. For studies showing overdispersion (variance exceeding binomial expectations typical in methylation data), apply the overdispersion='MN' parameter, which calculates a scaling factor φ = X²/(N-P) to adjust variance as φ·n_i·π̂_i·(1-π̂_i) and switches to an F-test, producing more stringent (higher) q-values. Extract differentially methylated bases using getMethylDiff() with dual filtering: q-value threshold (typically < 0.01) and percent methylation difference cutoff (typically > 25%). Separate hyper-methylated (high methylation in treatment) from hypo-methylated (low methylation in treatment) bases using the type parameter to assess directional changes.

Read the full file on GitHub · 107 lines

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. 9d ago First seen · 107 lines · 54 tokens per session scan A 53968382f9c0

Subscribe to this mod's changes

dna-methylation-differential-analysis is a skill published in the GitHub repository HolobiomicsLab/asb-skill-collections (15 stars, last pushed yesterday), licensed Apache-2.0. It adds 54 tokens to every session and 2,177 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 2026-09-03.

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