---
license: mit
base_model:
  - openai-community/gpt2
tags:
  - genomics
  - bioinformatics
  - DNA
  - sequence-classification
  - introns
  - exons
  - GPT
---

# Exons and Introns Classifier

GPT-2 finetuned model for **classifying DNA sequences** into **introns** and **exons**, trained on a large cross-species GenBank dataset (34,627 different species).

---

## Model Architecture

- Base model: GPT-2
- Approach: Full-sequence classification

---

## Usage

You can use this model through its own custom pipeline:

```python
from transformers import pipeline

pipe = pipeline(
  task="gpt2-exon-intron-classification",
  model="GustavoHCruz/ExInGPT",
  trust_remote_code=True,
)

out = pipe(
  {
    "sequence": "GCAGCAACAGTGCCCAGGGCTCTGATGAGTCTCTCATCACTTGTAAAG",
    "organism": "Homo sapiens",
    "gene": "HLA-C",
    "before": "GGTCTTTTTTTTTGTTCTACCCCAG",
    "after": "GTGAGATTCTGGGGAGCTGAAGTGG",
  }
)

print(out) # EXON
```

This model uses the same maximum context length as the standard GPT‑2 (1024 tokens), but it was trained on DNA sequences of up to 512 nucleotides. Additional context information (`organism`, `gene`, `before`, `after`) was also trained using specific rules:

- Organism and gene names were truncated to 10 characters
- Flanking sequences `before` and `after` were up to 25 nucleotides.

The pipeline follows these rules. Nucleotide sequences, organism, gene, before and after, will be automatically truncated if they exceed the limit.

---

## Custom Usage Information

Prompt format:

The model expects the following input format:

```
<|SEQUENCE|>[G][C][A][G]...
<|ORGANISM|>Homo sapiens
<|GENE|>HLA-C
<|FLANK_BEFORE|>[G][G][T][C]...
<|FLANK_AFTER|>[G][T][G][A]...
<|TARGET|>
```

- `<|SEQUENCE|>`: Full DNA sequence. Maximum of 512 nucleotides.
- `<|ORGANISM|>`: Optional organism name (truncated to a maximum of 10 characters in training).
- `<|GENE|>`: Optional gene name (truncated to a maximum of 10 characters in training).
- `<|FLANK_BEFORE|>` and `<|FLANK_AFTER|>`: Optional upstream/downstream context sequences. Maximum of 25 nucleotides.
- `<|TARGET|>`: Separation token for label prediction.

The model should predict the next token as the class label: `[EXON]` or `[INTRON]`.

---

## Dataset

The model was trained on a processed version of GenBank sequences spanning multiple species, available at the [DNA Coding Regions Dataset](https://huggingface.co/datasets/GustavoHCruz/DNA_coding_regions).

---

## Publications

- **Full Paper**  
  Achieved **2nd place** at the _Symposium on Knowledge Discovery, Mining and Learning (KDMiLe 2025)_, organized by the Brazilian Computer Society (SBC), held in Fortaleza, Ceará, Brazil.  
  DOI: [https://doi.org/10.5753/kdmile.2025.247575](https://doi.org/10.5753/kdmile.2025.247575).
- **Short Paper**  
  Presented at the _IEEE International Conference on Bioinformatics and BioEngineering (BIBE 2025)_, held in Athens, Greece.  
  DOI: [https://doi.org/10.1109/BIBE66822.2025.00113](https://doi.org/10.1109/BIBE66822.2025.00113).

---

## Training

- Trained on an architecture with 8x H100 GPUs.

---

## Metrics

**Average accuracy:** **0.9985**

| Class      | Precision | Recall | F1-Score |
| ---------- | --------- | ------ | -------- |
| **Intron** | 0.9977    | 0.9973 | 0.9975   |
| **Exon**   | 0.9988    | 0.9990 | 0.9989   |

---

### Notes

- Metrics were computed on a full isolated test set.
- The classes follow a ratio of approximately 2 exons to one intron, allowing for direct interpretation of the scores.
- The model can operate on raw nucleotide sequences without additional biological features (e.g. organism, gene, before or after).

---

## GitHub Repository

The full code for **data processing, model training, and inference** is available on GitHub:  
[CodingDNATransformers](https://github.com/GustavoHCruz/CodingDNATransformers)

You can find scripts for:

- Preprocessing GenBank sequences
- Fine-tuning models
- Evaluating and using the trained models