EpiChronos

EpiChronos is a high-performance, unified downstream DNA methylation and biological aging analysis suite. Written in memory-efficient, multi-threaded Python (built on Polars and NumPy/SciPy), EpiChronos overcomes the memory barriers and platform fragmentation of traditional R-Bioconductor pipelines, providing a scalable solution that integrates microarray, sequencing (WGBS, RRBS, EM-seq), and long-read methylation data in a single tool.

🚀 Key Features

• Unified Multi-Platform Support: Read and align standard Bismark .cov sequencing files, array-based beta matrices, and coordinate datasets seamlessly into a common coordinate-centric format.
• Order-of-Magnitude Performance Gains: Leverage a fully multi-threaded Polars data engine to run DML/DMR calling on millions of cytosines in seconds, bypassing the R-Bioconductor memory wall.
• Vectorized Welch's t-test with Welch–Satterthwaite df: High-fidelity statistical comparisons between phenotypic cohorts using highly parallelized matrix algebra and rigorous degrees of freedom to avoid pooled-variance errors.
• Assembly-Aware Epigenetic Aging Clocks: Built-in Horvath, Hannum, and Pacemaker clock calculations with dynamic coordinate liftover mapping (GRCh37/GRCh38) powered by pyliftover to prevent silent coordinate mismatches.
• Robust Missing-Value Imputation: High-fidelity cohort-mean and standard public reference-mean imputation for missing CpGs in sparse sequencing samples, resolving a major bottleneck where missing sites cause clock calculations to crash.
• Hypergeometric Pathway Enrichment (MSigDB Hallmarks): High-speed overrepresentation analysis using Legally compliant, CC BY 4.0 licensed MSigDB Hallmark gene sets.
• Interactive Standalone HTML Reports: Compile quality control, global PCA projections, Volcano plots of differentially methylated loci (DMLs), and epigenetic age acceleration graphs into a single shareable interactive dashboard.

📦 Installation

To install EpiChronos in development mode:

git clone https://github.com/Rashidmstar12/EpiChronos.git
cd EpiChronos
pip install -e .

Dependencies

EpiChronos is built to be extremely lightweight and requires only:

• polars >= 0.20.0 (for high-speed lazy-evaluated dataframes)
• numpy >= 1.24.0 (for vectorized math)
• scipy >= 1.10.0 (for statistical distributions)
• plotly >= 5.14.0 (for interactive visualization)
• pyarrow >= 12.0.0 (for Arrow memory management)
• pyliftover >= 0.6.1 (for dynamic assembly liftover translation)

⚡ Quick Start

Analyze a full sequencing cohort in under 15 lines of Python:

import epichronos as ec

# 1. Load and align sequencing samples by genomic coordinates
samples = ["Ctrl_1", "Ctrl_2", "Treat_1", "Treat_2"]
filepaths = [f"data/{s}.cov" for s in samples]
metadata = {"Ctrl_1": "Young", "Ctrl_2": "Young", "Treat_1": "Old", "Treat_2": "Old"}

dataset = ec.load_bismark_coverage(filepaths, samples, min_cov=5)
dataset.metadata = metadata

# 2. Call Differentially Methylated Loci & Regions (DMLs / DMRs)
dml_df = ec.call_dmls(dataset, ["Ctrl_1", "Ctrl_2"], ["Treat_1", "Treat_2"])
dmr_df = ec.call_dmrs(dml_df, p_cutoff=0.05, max_dist=1000, min_sites=3)

# 3. Calculate Epigenetic Biological Age (Horvath Clock)
true_ages = {"Ctrl_1": 22.0, "Ctrl_2": 26.0, "Treat_1": 60.0, "Treat_2": 65.0}
clock_df = ec.calculate_biological_age(dataset, clock_name="horvath", chronological_ages=true_ages)

# 4. Export a premium interactive HTML report
ec.generate_report(dataset, dml_df, dmr_df, clock_df, "epichronos_dashboard.html")

💾 Memory Efficiency & RAM Benchmarks

By storing aligned coordinates in memory-efficient Apache Arrow columnar buffers via Polars, EpiChronos eliminates the boxing overhead of Python objects and the R garbage collector. This enables comprehensive analysis of whole-genome datasets on a standard consumer laptop.

Estimated RAM Footprint (Single File Ingestion)

• Microarray Data (EPIC v2 / EPIC / 450K) (~930k sites): ~35 MB – 50 MB of RAM
• Reduced Representation Sequencing (RRBS) (~2M sites): ~80 MB – 120 MB of RAM
• Whole Genome Sequencing (WGBS) / Nanopore (~28M sites, 1.5 GB file on disk):
  • Unfiltered (Full Genome): ~1.0 GB – 1.2 GB of RAM
  • With Coverage Filtering (min_cov=5): ~500 MB – 700 MB of RAM

📊 In-Memory Scaling vs. R-Bioconductor

To load and align a single Whole-Genome Bisulfite Sequencing (WGBS) sample (28 million CpGs):

📐 Pipeline Blueprint

Raw Methylation Input
  ├── Bismark Coverage (.cov)
  ├── Microarray Beta-Value Matrix
  └── Long-Read bedGraph
       │
       ▼
 epichronos.core.MethylationDataset (Polars-aligned coordinate framework)
  ├── filter_by_coverage()
  ├── filter_by_variance()
  └── impute_missing()
       │
       ├──────────────────────────────┐
       ▼                              ▼
epichronos.stats               epichronos.clocks
  ├── call_dmls()                ├── calculate_biological_age()
  └── call_dmrs()                └── (Cohort & Ref-mean Imputation)
       │                              │
       └──────────────┬───────────────┘
                      ▼
               epichronos.viz
                 └── generate_report() -> Standalone HTML Report

🛡️ License

Distributed under the MIT License. See LICENSE for more information.