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arXiv · 2603.10885

Continuous Diffusion Transformers for Designing Synthetic Regulatory Elements

Jonathan Liu·Kia Ghods
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Abstract

We present a parameter-efficient Diffusion Transformer (DiT) for generating 200bp cell-type-specific regulatory DNA sequences. By replacing the U-Net backbone of DNA-Diffusion with a transformer denoiser equipped with a 2D CNN input encoder, our model matches the U-Net's best validation loss in 13 epochs (60$\times$ fewer) and converges 39% lower, while reducing memorization from 5.3% to 1.7% of generated sequences aligning to training data via BLAT. Ablations show the CNN encoder is essential: without it, validation loss increases 70% regardless of positional embedding choice. We further apply DDPO finetuning using Enformer as a reward model, achieving a 38$\times$ improvement in predicted regulatory activity. Cross-validation against DRAKES on an independent prediction task confirms that improvements reflect genuine regulatory signal rather than reward model overfitting.

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Jonathan Liu, Kia Ghods. 2026-03-11. Continuous Diffusion Transformers for Designing Synthetic Regulatory Elements. https://arxiv.org/abs/2603.10885

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