What question did this study set out to answer?

The study aimed to develop an adenine base editor with reduced off-target effects for safer clinical applications.

February 8, 2026Protein & Cell0 citationsOpen Access

Therapeutic adenine base editor with minimized off-target effects

YSYongsen SunAgricultural Genomics Institute at Shenzhen NYNana YanLongyan University FHFeng HuAgricultural Genomics Institute at Shenzhen

Key Points

The study aimed to develop an adenine base editor with reduced off-target effects for safer clinical applications.
Performed saturation mutagenesis on the deaminase of ABE8e to obtain ABE8eY149V.
Used two-cell embryo injection to analyze editing effects on SNVs.
Fused ABE8eY149V with various Cas homologs to test target range.
Evaluated the effects of ABE8eY149V editing on the Hpd gene in mice models of hereditary tyrosinemia.
ABE8e showed significantly higher off-target effects compared to spontaneous SNVs in controls.
ABE8eY149V provided high editing efficiency without detectable off-target effects.
Fusion of TadA8eY149V with other Cas homologs expanded the target range.
Editing the Hpd gene using ABE8eY149V prevented lethality in a mouse model of hereditary tyrosinemia.

Abstract

Abstract Genome-wide off-target effect poses a safety risk for clinical use of adenine base editor (ABEs), among which ABE8e is one of the most efficient. Two-cell embryo injection (GOTI) analysis showed that the rate of genome-wide single nucleotide variants (SNVs) in ABE8e-edited cells was ∼30-fold higher than that of spontaneous SNVs in control cells, indicating prevalent off-target effects of ABE8e, but no off-target effect for ABE7.10, from which ABE8e was derived. We performed saturation mutagenesis of eight amino acid sites of the deaminase (TadA8e) within ABE8e and obtained ABE8eY149V that exhibited high editing efficiency without detectable off-target effect. Furthermore, TadA8eY149V could be fused with other Cas homologs (PAM-relaxed SpRY, hypercompact SaKKH, or IscB) to expand its target range. Finally, ABE8eY149V editing of hydroxyphenylpyruvate dioxygenase (Hpd) gene prevented lethality in hereditary tyrosinemia type I mice. The high efficiency and fidelity of ABE8eY149V suggest its potential application in ABE-based gene therapies.

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