VisuaMiTRA - a Tandem Repeat Visualizer

VisuaMiTRa (pronounced vi-shu-uh-mee-truh, IPA: /vɪʃuəmiːtrə/, Sanskrit: विश्वमित्र) is a specialized visualization tool for Tandem Repeat alleles, designed for a concise overview of motif decomposition, and corresponding epigenetic methylation signals. The name expands to VISUAlisation of Motifs & Methylation in Tandem Repeat Alleles.

The name is derived from the Sanskrit word Vishvamitra (विश्वमित्र), meaning "Friend of the Universe." In this context, VisuaMiTRa acts as a companion to the researcher, providing a clear comprehensive overview of tandem repeat complexity. By layering structural motifs and methylation data into a single, intuitive interface, it transforms dense genomic variant files into an accessible and navigable landscape.

Motivation

The high-resolution genotypes and methylation profiles generated by ATaRVa require an integrated perspective to be clearly interpreted. VisuaMiTRa is the essential next step, transforming VCF data outputs into a visual interface where structural motifs and epigenetic methylation signals align. Providing this overview enables researchers to rapidly validate and navigate ATaRVa's results at scale.

Table of Contents

• Motivation
• Installation
• Usage
  • Workflow
  • Features
• Data Requirements
• Citation
• Contacts

Installation

VisuaMiTRa is available as a Python package that manages both the backend server and the compiled frontend automatically.

Prerequisites: Python 3.9+ and htslib (for Tabix functionality).

Create and activate a python environment (recommended)

source venv/bin/activate  # On Windows use: venv\Scripts\activate

Install the package

pip install visuamitra

Usage

Visuamitra v1.0.4 is compatible with ATaRVa ( > v0.7.0)

Browser mode

Once installed, to launch the tool and manually select or upload your VCF files via the web interface:

visuamitra

CLI Mode

Rather than browser upload, passing the vcf file path as argument will launch visuamitra.

visuamitra /path/to/your/file.vcf.gz

Note: The corresponding .tbi index file must reside in the same directory as the target .vcf.gz file, with same name (e.g., file.vcf.gz.tbi).

Access: The application will initialize and host the interface on port 8088. Open your web browser and navigate to http://localhost:8088.

Workflow

Fig 1: Workflow of visuamitra

VisuaMiTRa uses a high-performance backend designed for rapid random access and minimal memory overhead.

Data Ingestion: Users provide a Tabix-indexed VCF file and its .tbi index (generated by ATaRVa).

Validation: FastAPI performs a preflight check using pysam to ensure the requested genomic region exists, preventing empty streams and invalid coordinate errors.

Pagination: To handle large data, the tool uses Base64-encoded cursors which allows to 'bookmark' positions and fetch subsequent pages without re-scanning entire files.

Optimized Streaming: Data is streamed in small chunks and delivered in real-time to ensure the tool remains fast and lightweight, even with very large files.

Reactive Visualization: React parses the TSV stream into an interactive SVG canvas, mapping structural motifs and methylation probabilities in real-time.

Fig 2: visuamitra

✨ Features

VisuaMiTRa provides a comprehensive and intuitive overview of tandem repeat complexity.

👥 Multi-Sample Comparative Analysis

VisuaMiTRa now supports the simultaneous visualization of multiple samples from a merged VCF.

• Dynamic Selection: Choose which samples to display using a searchable dropdown menu.

• Synchronized Scaling: All selected samples are rendered on a shared genomic scale, allowing for direct visual comparison of allele lengths, motifs and methylation patterns across cohorts.

🧬 Dual View for Motifs & Methylation

• VisuaMiTRa features independent tabs for motif decomposition & methylation that maintain strict allele-length consistency, enabling precise comparison across multiple samples.

📍 Effortless Navigation

• Target specific loci using coordinate inputs (Chr, Start, End) or manually browse thousands of records smoothly, alongside an indicator with a track of genomic context in Chromosome. (Note: visuamitra v1.0.4 currently supports Hg38 assembly reference only.)

Fig 3: Location inputs

Fig 4: Chromosome context

📏 Interactive Interface

• Magnify in or out of intricate regions to ease data interpretation.

• Hover over motif segments to instantly view repeat counts. Methylation levels markers for clearer visualisation.

• Customize view with professional color palettes, scales & fonts.

• The expected motif can be viewed in interchangeable colors, within a palette as well (New in v1.0.4).

Fig 5: Repeat counts

Fig 6: Methylation markers

💾 Download plots

• Publication-Ready SVGs: Download high-resolution vector graphics of the viewed genomic locations.

• Genomic plots could also be downloaded as PNG/JPGs.

📊 Overview Tab (New in v1.0.4)

• A third tab with a comparitive summary of the samples selected.

• Encompasses plots showing variation of methylation, 'the copy number of the longest pure motif found', with allele lengths.

Fig 7: Overview tab

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Contacts

Authors: Siddharth K, Abishek Kumar, Divya Tej Sowpati

Email: Siddharth K - siddharthk at csirccmb dot org

Abishek Kumar S - abishekks at csirccmb dot org

Divya Tej Sowpati - tej at csirccmb dot org