---
license: apache-2.0
tags:
- dna
- genomics
- mutation
- omni-dna
- sad
base_model: Nhoodie/omni-dna-ici-dc
pipeline_tag: text-generation
---

## ⚠️ IMPORTANT WARNING — Model Effectiveness

**This model's reported SAD coefficient is unreliable.** The ICI-DC (S1) and SAD (S2) training stages both underfit near-instantly. The SAD coefficient was calculated from training hyperparameters (synthetic_pairs × epochs / real_pairs × epochs × LR_factor), NOT from converged training. The model never reached a stable training state that would justify the coefficient value.

Subsequent testing revealed that the unmodified base Omni-DNA-20M model achieves **0.951 AUC** on discriminative mutation detection with raw DNA prompts — significantly outperforming ALL fine-tuned variants including this one. Fine-tuning with ICI-DC synthetic data systematically degraded the base model's innate mutation discrimination capability.

**This model is preserved for historical and reproducibility purposes only.**

---


# Omni-DNA SAD Checkpoint

**Sequential Attenuation Denoising (SAD)** — ICI-DC checkpoint fine-tuned on real mutation data.

Starting from the [ICI-DC checkpoint](https://huggingface.co/Nhoodie/omni-dna-ici-dc), this model
undergoes attenuation: real mutation pairs at 10x lower learning rate. Weights that don't contradict
real data persist from ICI-DC; contradicted patterns get corrected.

## SAD Training Details

| Parameter | Value |
|---|---|
| Base model | `Nhoodie/omni-dna-ici-dc` (ICI-DC pre-trained) |
| Training data | 3,317 real mutation pairs |
| Epochs | 5 |
| Learning rate | 1e-5 (10x lower than ICI-DC) |
| **SAD coefficient** | **4.89** (81,120 synthetic exposures / 16,585 real exposures) |
| Batch size | 32 effective |
| Precision | fp32 |

> **Note**: SAD coefficient of 4.89 is considered too high. A coefficient of ~1.5 was also tested
> (16 real epochs) with similar results. See benchmarks below.

## Multi-Axis Benchmark (100 test pairs, 4 models)

### Axis 6: Discriminative (most important)

| Model | AUC | Best F1 | Score Gap |
|-------|:---:|:---:|:---:|
| Base Omni (no fine-tune) | 0.588 | 0.688 | 25.6 |
| [ICI-DC](https://huggingface.co/Nhoodie/omni-dna-ici-dc) | 0.887 | 0.858 | 370.2 |
| **SAD coeff=4.89 (this)** | **0.904** | **0.862** | **411.4** |
| SAD coeff=1.5 | 0.908 | 0.862 | 413.7 |

### Axis 5: Mutation Surprise

| Model | Surprise | p-value | Interpretation |
|-------|:---:|:---:|:---|
| Base Omni | +0.777 | <0.0001 | Expects parent (mutations are surprising) |
| ICI-DC | -0.216 | 0.0001 | Expects mutations everywhere |
| **SAD coeff=4.89** | -0.203 | 0.0003 | Partially attenuated |
| SAD coeff=1.5 | -0.169 | 0.0026 | More attenuation |

### Full 6-Axis Comparison

| Axis | Metric | Base | ICI-DC | SAD 4.89 | SAD 1.5 |
|---|---|:---:|:---:|:---:|:---:|
| A1: Detection | Recall | 0.511 | 0.518 | 0.517 | 0.497 |
| A2: Logits | Top-3 acc | 0.846 | 0.846 | 0.846 | 0.846 |
| A3: Ti/Tv | Predicted ratio | 0.20 | 0.41 | 0.42 | 0.43 |
| A4: Embeddings | Seq AUC | 0.41 | 0.35 | 0.40 | 0.40 |
| A5: Surprise | ΔLL | +0.78 | -0.22 | -0.20 | -0.17 |
| **A6: Discrim.** | **AUC** | **0.588** | **0.887** | **0.904** | **0.908** |

### Interpretation

- **ICI-DC provides the main training signal** (AUC 0.59→0.89). Synthetic data builds a strong
  internal representation of valid mutation pairs.
- **SAD fine-tunes that representation** (0.887→0.908). The attenuation step does help, but the
  marginal gain over ICI-DC is modest.
- **The model is a judge, not a generator.** 90.8% discriminative AUC but ~30% generative recall.
  The representations encode mutation structure, but autoregressive decoding can't access it efficiently.
- **Ti/Tv ratio converges** from 0.20 (base) to 0.43 (SAD 1.5), approaching the biological value of 0.48.

## Usage

```python
from transformers import AutoTokenizer, AutoModelForCausalLM

tokenizer = AutoTokenizer.from_pretrained("Nhoodie/omni-dna-sad-mutation", trust_remote_code=True)
model = AutoModelForCausalLM.from_pretrained("Nhoodie/omni-dna-sad-mutation", trust_remote_code=True)

# Score a mutation pair (discriminative use)
prompt = "mutate: ATGGCTAGCTGA -> ATAGCTGGCTAA"
logits = model(**tokenizer(prompt, return_tensors="pt")).logits
```

## Related

- **[Nhoodie/omni-dna-ici-dc](https://huggingface.co/Nhoodie/omni-dna-ici-dc)** — ICI-DC checkpoint (synthetic-only)
- **[Nhoodie/omni-dna-sad-mutation-dataset](https://huggingface.co/datasets/Nhoodie/omni-dna-sad-mutation-dataset)** — Training data

## Source Code

Git commit: `7be4e73` (branch `dev/sad-omni-hyena`, private repo)

## Citation

- Omni-DNA: Zehui127 et al.
- HyenaDNA: Nguyen et al., NeurIPS 2023
- ENBED: Malusare et al., Bioinformatics Advances, 2024 (arXiv: 2311.02333)