Compact CRISPR enzyme advances in vivo gene editing potential

Tuesday 14 April 2026 - 08:40

By: Dakir Madiha

Compact CRISPR enzyme advances in vivo gene editing potential

Researchers at University of Texas at Austin have engineered a compact CRISPR enzyme that fits inside viral delivery systems used in gene therapy, marking a step toward practical in vivo genome editing. The work, funded by the National Institutes of Health, was published in Nature Structural & Molecular Biology.

Current CRISPR systems used in clinical settings are often too large to be packaged into adeno-associated virus vectors, or AAVs, which are widely used to deliver gene therapies to target tissues. This size limitation has restricted most CRISPR applications to cells edited outside the human body.

The Texas team, working with Metagenomi Therapeutics, identified a naturally occurring enzyme known as Al3Cas12f that is small enough to fit into AAV vectors. Using imaging techniques and machine learning, they analyzed its structure and found it forms a more stable complex than similar enzymes.

Lead author David Taylor said the enzyme appears effectively preassembled and ready to function soon after its components are produced, which contributes to its stability and performance.

The researchers then engineered a modified version called Al3Cas12f RKK. This variant increased gene editing efficiency from below 10 percent to more than 80 percent across several genomic targets in human cells. In one frequently targeted region, efficiency reached 90 percent.

The team tested the system in human cell lines originally derived from a leukemia patient. They targeted genes linked to cancer, atherosclerosis, and amyotrophic lateral sclerosis. The next phase will involve integrating the enzyme into AAV vectors and evaluating its performance under conditions closer to clinical use.

Erica Brown said targeted delivery of gene editing systems has broad clinical implications and that the findings move the field closer to real-world applications.

The study reflects a wider push to develop compact CRISPR systems compatible with in vivo delivery. If validated in clinical settings, such tools could expand treatment options for diseases that currently lack effective gene therapies.