NTv3_tracks / README.md
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metadata
library_name: transformers
tags:
  - genomics
  - dna
  - biology
  - ntv3
  - long-range
  - functional-genomics
license: other
license_name: instadeep-open-model-licence
license_link: https://huggingface.co/InstaDeepAI/NTv3_tracks/blob/main/MODEL-LICENSE.md
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NTv3 Tracks

Predicts functional genomic tracks at single-base resolution, conditioned on species: gene expression, histone marks, transcription-factor binding and chromatin accessibility, from DNA sequence alone.

Built on the NTv3_pretrained backbone and post-trained on 16,262 tracks across 15 species, then finetuned on a mix of input lengths so it can be used from 16 kb to 1 Mb.

Architecture

The NTv3 U-Net trunk (a convolutional encoder, a transformer tower at 1/128 resolution and a deconvolutional decoder back to base resolution) with prediction heads on top. Species conditioning is applied through FiLM modulation inside the trunk and at the head.

Parameters 711,256,680
Resolution 1 bp
Input length 16,384 to 1,048,576 bp
Vocabulary 16 tokens (soft-masked)
Species 15
Output channels 7,362
Precision float32

Usage

import json

import torch
from huggingface_hub import hf_hub_download
from transformers import AutoModel, AutoTokenizer

repo = "InstaDeepAI/NTv3_tracks"
model = AutoModel.from_pretrained(repo, trust_remote_code=True).eval()
tokenizer = AutoTokenizer.from_pretrained(repo, trust_remote_code=True)
metadata = json.load(open(hf_hub_download(repo, "track_metadata.json")))

# The input length must be a multiple of 128; see "Input length" below.
sequence = "ACGT" * 4_096

batch = tokenizer([sequence], return_tensors="pt", add_special_tokens=False)
species = [torch.tensor([metadata["species_vocabulary"]["human"]])]

with torch.no_grad():
    out = model(**batch, conditions_tokens=species)

out.bigwig_tracks_logits.shape  # (1, 6144, 7362)

A 1 Mb forward pass needs a GPU with about 32 GB of memory or more; move the model and the batch to it with .to("cuda").

Outputs are reachable both as attributes (out.bigwig_tracks_logits) and as keys (out["bigwig_tracks_logits"]). An attention_mask is accepted and ignored: the model derives its own mask from the pad token.

trust_remote_code=True is required. The modelling code is not in this repository: config.json resolves it from InstaDeepAI/NTv3_pretrained, which therefore has to be reachable as well.

Outputs

Key Shape What it is
bigwig_tracks_logits (batch, length × 0.375, 7362) Predicted track signal, one channel per track
embedding (batch, length, 1024) Decoder output, one vector per base
logits (batch, length, 16) Masked-token prediction
species_logits (batch, 21) Auxiliary head from training. Not a usable species classifier: it predicts the mask token on real sequence.

The region interface

For a genomic region rather than a bare sequence, the pipeline fetches the window, conditions on the species and labels the output:

from transformers import pipeline

predictor = pipeline("ntv3-tracks", model="InstaDeepAI/NTv3_tracks",
                     trust_remote_code=True)

out = predictor({"chrom": "chr11", "start": 5_219_320, "end": 5_235_704,
                 "species": "human"})

out.tracks.shape      # (6144, 7362)  positions x tracks
out.coordinates       # (5224440, 5230584)  what the predictions span
out.track("kai1")     # one track's signal, by id

The pipeline downloads the window, soft-masked, from the UCSC Genome Browser API, so start and end are 0-based, end-exclusive coordinates on the species' assembly (metadata["species_to_assembly"]). UCSC serves every assembly here except wheat (IWGSC). For wheat, or for a sequence of your own, pass {"seq": ..., "species": ...} instead.

out.coordinates is the span the predictions cover, the central 37.5% of the window (see below). It is None when you pass seq.

Reading the predictions

The output does not cover the whole window. It covers the central 37.5%. A 1 Mb input yields predictions for the central 393,216 bp. The edges are consumed as context. Tile your windows with overlap if you need continuous coverage.

Channel i is track i of that species' list. track_metadata.json holds bigwigs_per_file_assembly, mapping each assembly to its ordered track ids:

track_ids = metadata["bigwigs_per_file_assembly"]["hg38"]
signal = out["bigwig_tracks_logits"][0, :, 0]  # track_ids[0]

Species have different numbers of tracks and the head is padded to the widest one, so only the first len(track_ids) channels are meaningful for a given species. The rest is padding.

The species id comes from the same file. metadata["species_vocabulary"] maps each species name to its id. Passing the wrong id gives you another species' tracks, silently.

Track lists are keyed by assembly, not by species, so metadata["species_to_assembly"] gives the link:

assembly = metadata["species_to_assembly"]["human"]        # "hg38"
track_ids = metadata["bigwigs_per_file_assembly"][assembly]

The predictions are in the scaled space the model was trained on, not in signal units. Each track was divided by its genome-wide mean, RNA-seq tracks were then raised to the power 0.75, and values above 10 were soft-clipped. The per-track means and the RNA-seq flags ship in track_metadata.json, in the same order as the track ids, so the predictions can be converted back to signal units:

import numpy as np

def to_signal(predictions, assembly, track_ids):
    """Converts predictions for these tracks, (..., len(track_ids)), to signal units."""
    all_ids = metadata["bigwigs_per_file_assembly"][assembly]
    index = [all_ids.index(track_id) for track_id in track_ids]
    mean = np.array(metadata["track_means_per_file_assembly"][assembly])[index]
    rna_seq = np.array(metadata["rna_seq_per_file_assembly"][assembly])[index]
    x = np.where(predictions > 10, (predictions + 10) ** 2 / 40, predictions)
    x = np.where(rna_seq, x ** (1 / 0.75), x)
    return x * mean

Input length

The model was finetuned from NTv3_tracks_1mb on inputs of 16, 32, 65, 131, 262 and 524 kb and 1 Mb. It matches that model at 1 Mb and stays accurate on the shorter inputs, where the 1 Mb model does not. Accuracy is still highest at 1 Mb, where the model sees the most context. Lengths between the trained ones, and lengths outside 16 kb to 1 Mb, were not evaluated.

Pearson correlation of predicted and measured tracks against input length, for
NTv3_tracks and NTv3_tracks_1mb

Pearson correlation between predicted and measured tracks (log1p-transformed, 1 bp) on held-out test regions of the 15 species, by input length. Right: the change per species.

Input requirements

Length must be a multiple of 128, the total downsampling factor of the trunk. Use one of the trained lengths above where you can.

Pass soft-masked sequence as it is. This model reads a 16-symbol alphabet: A C G T N and their lowercase counterparts a c g t n. Lowercase marks repeat-masked bases, which the model was trained on, so do not upper-case your input. NTv3_pretrained uses the 11-symbol uppercase alphabet instead, so the two tokenizers are not interchangeable.

Characters outside the vocabulary become <unk> and the sequence keeps its length.

Intended use

Predicting functional track signal from sequence for the species the model covers; comparing predicted signal between alleles or between designed sequences; and as a backbone for fine-tuning on your own track data.

Out of scope

Not a clinical or diagnostic tool. Predicted signal is a model output, not a measurement.

Species outside the 15 it was trained on are out of distribution. The model still returns predictions for them, but they have not been validated.

Limitations

Predictions are conditioned on species and sequence only. There is no input for cell type, tissue, developmental stage or treatment beyond what the track panel itself encodes, so the model cannot be steered to a condition that is not already a track.

Accuracy varies substantially across assays, across species and across genomic regions. The panel is not balanced: some species contribute many more tracks than others, and performance follows that. Treat a single channel's output as weaker evidence than an aggregate.

The 37.5% crop is fixed by training; it is not an inference setting.

Related models

Model For
NTv3_tracks_1mb The 1 Mb specialist this model was finetuned from; the NTv3 paper's main results use it
NTv3_pretrained Embeddings, masked-token prediction, fine-tuning
NTv3_annot_{mammals,plants,insects} Ab initio gene annotation, one model per clade

Licence

Released under the InstaDeep Open Model Licence. The licence restricts output as well as weights, so predicted tracks carry the same terms. Read it before building on the model commercially.

Citation

@article{ntv3,
  title   = {A multispecies foundation model for genome function prediction, gene annotation and sequence design},
  author  = {Boshar, Sam and Evans, Benjamin and Tang, Ziqi and Adel, Yanis and Bornachot, Yohan and Sidbon, Shawn and Lorbeer, Franziska K. and Picard, Armand and Rajesh, Chandana and Seitz, Evan and Emms, David and Mendoza-Revilla, Javier and Hernandez, Ariana and Al-Ani, Fatimah and Karch, Tristan and Schiff, Yair and Lopez, Marie and Laterre, Alexandre and Beguir, Karim and Koo, Peter and Kuleshov, Volodymyr and Stark, Alexander and de Almeida, Bernardo P. and Pierrot, Thomas},
  journal = {bioRxiv},
  year    = {2026},
  doi     = {10.64898/2025.12.22.695963},
  url     = {https://www.biorxiv.org/content/10.64898/2025.12.22.695963}
}